[Joint Matrix][E2E] Remove xfail for 2 tests (#13605)

Remove xfail for Matrix/XMX8/joint_matrix_bf16_fill_k_cache_unroll.cpp
and XMX8/joint_matrix_int8_vnni.cpp

Resolves #13593

Author: YuriPlyakhin

sycl/test-e2e/Matrix/XMX8/joint_matrix_bf16_fill_k_cache_unroll.cpp

@@ -6,7 +6,6 @@
 //
 //===----------------------------------------------------------------------===//
 // REQUIRES: matrix-xmx8
-// XFAIL:gpu
 
 // RUN: %{build} -mllvm -inline-threshold=2000 -ffp-model=precise -o %t.out -DMANUAL_UNROLL
 // RUN: %{run} %t.out

sycl/test-e2e/Matrix/XMX8/joint_matrix_int8_vnni.cpp

@@ -10,13 +10,8 @@
 // RUN: %{build} -o %t.out
 // RUN: %{run} %t.out
 
-// XFAIL: *
-
 #include "../common.hpp"
 
-using namespace sycl;
-using namespace sycl::ext::oneapi::experimental::matrix;
-
 #define SG_SZ 8
 constexpr size_t TN = 8;