[MPS][BE] Do not crash if Metal function can not be found (pytorch#116938)

As [`newFunctionWithName:`](https://developer.apple.com/documentation/metal/mtllibrary/1515524-newfunctionwithname) does not accept error argument, do not attempt to print it as it'll be guaranteed `nil` at that point, that results in a classic null pointer dereference, when `TORCH_CHECK` will attempt to construct `std::string` from it. See below backtrace for example:
```
 thread #1, queue = 'metal gpu stream', stop reason = EXC_BAD_ACCESS (code=1, address=0x0)
    frame #0: 0x000000018a316dc4 libsystem_platform.dylib`_platform_strlen + 4
    frame #1: 0x00000001471011bc libtorch_cpu.dylib`std::__1::__constexpr_strlen[abi:v160006](__str=0x0000000000000000) at cstring:114:10
    frame #2: 0x0000000147100c24 libtorch_cpu.dylib`std::__1::char_traits<char>::length(__s=0x0000000000000000) at char_traits.h:220:12
  * frame #3: 0x0000000147100bf0 libtorch_cpu.dylib`std::__1::basic_ostream<char, std::__1::char_traits<char>>& std::__1::operator<<[abi:v160006]<std::__1::char_traits<char>>(__os=0x000000016fdfb3a0, __str=0x0000000000000000) at ostream:901:57
    frame pytorch#4: 0x0000000147100bb4 libtorch_cpu.dylib`std::__1::basic_ostream<char, std::__1::char_traits<char>>& c10::detail::_str<char const*>(ss=0x000000016fdfb3a0, t=0x000000016fdfb5d0) at StringUtil.h:55:6
    frame pytorch#5: 0x00000001471007ac libtorch_cpu.dylib`std::__1::basic_ostream<char, std::__1::char_traits<char>>& c10::detail::_str<char const*, char const*>(ss=0x000000016fdfb3a0, t=0x000000016fdfb4f8, args=0x000000016fdfb5d0) at StringUtil.h:68:10
    frame pytorch#6: 0x0000000147101444 libtorch_cpu.dylib`std::__1::basic_ostream<char, std::__1::char_traits<char>>& c10::detail::_str<std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char>>, char const*, char const*>(ss=0x000000016fdfb3a0, t="index_select_32bit_idx32", args=0x000000016fdfb4f8, args=0x000000016fdfb5d0) at StringUtil.h:68:10
    frame pytorch#7: 0x0000000147101404 libtorch_cpu.dylib`std::__1::basic_ostream<char, std::__1::char_traits<char>>& c10::detail::_str<char const*, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char>>, char const*, char const*>(ss=0x000000016fdfb3a0, t=0x000000016fdfb500, args="index_select_32bit_idx32", args=0x000000016fdfb4f8, args=0x000000016fdfb5d0) at StringUtil.h:68:10
    frame pytorch#8: 0x000000014710137c libtorch_cpu.dylib`c10::detail::_str_wrapper<char const*, std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char>> const&, char const*, char const* const&>::call(args=0x000000016fdfb500, args="index_select_32bit_idx32", args=0x000000016fdfb4f8, args=0x000000016fdfb5d0) at StringUtil.h:75:5
    frame pytorch#9: 0x0000000147101310 libtorch_cpu.dylib`decltype(auto) c10::str<char [53], std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char>>, char [10], char const*>(args={a\xcb\xa7H\x01\0\0\0}, args="index_select_32bit_idx32", args={\x96\xcb\xa7H\x01\0\0\0}, args=0x000000016fdfb5d0) at StringUtil.h:111:10
    frame pytorch#10: 0x0000000147100210 libtorch_cpu.dylib`decltype(auto) c10::detail::torchCheckMsgImpl<char [53], std::__1::basic_string<char, std::__1::char_traits<char>, std::__1::allocator<char>>, char [10], char const*>((null)="Expected indexFunction to be true, but got false.  (Could this error message be improved?  If so, please report an enhancement request to PyTorch.)", args={a\xcb\xa7H\x01\0\0\0}, args="index_select_32bit_idx32", args={\x96\xcb\xa7H\x01\0\0\0}, args=0x000000016fdfb5d0) at Exception.h:453:10
    frame pytorch#11: 0x00000001470fffe8 libtorch_cpu.dylib`at::mps::MPSDevice::metalIndexingPSO(this=0x0000600000381670, kernel="index_select_32bit_idx32") at MPSDevice.mm:62:3
```

This was introduced by pytorch#99855 that replaced `newFunctionWithName:constantValues:error:` with `newFunctionWithName:`
Pull Request resolved: pytorch#116938
Approved by: https://github.com/Skylion007

Author: malfet

aten/src/ATen/mps/MPSDevice.mm

@@ -59,11 +59,7 @@ static inline MTLLanguageVersion getMetalLanguageVersion(const id<MTLDevice>& de
 
   id<MTLFunction> indexFunction =
       [[indexing_lib newFunctionWithName:[NSString stringWithUTF8String:kernel.c_str()]] autorelease];
-  TORCH_CHECK(indexFunction,
-              "Failed to create specialized function state object: ",
-              kernel,
-              ", error: ",
-              [[error description] UTF8String]);
+  TORCH_CHECK(indexFunction, "Can't find function ", kernel);
 
   state = [_mtl_device newComputePipelineStateWithFunction:indexFunction error:&error];
   TORCH_CHECK(state, error.localizedDescription.UTF8String);