Remove FMV implement part stuff

Author: BeMg

riscv-c-api.md

@@ -728,23 +728,4 @@ statements, including both RISC-V specific and common operand modifiers.
 
 ## Function Multi-version
 
-Function multi-versioning(FMV) provides an approach to selecting the appropriate function according to the runtime environment. This feature is triggered by `target_version/target_clones` function attribute. The compiler generates the resolver function based on the IFUNC mechanism. It expects that there is an API in the runtime environment for FMV to check if it fulfills all extension requirements.
-
-### Runtime Feature API
-
-Here is the prototype of that API.
-
-```
-bool __riscv_ifunc_select(char *FeatureString)
-```
-
-Where FeatureString is a string that concatenates all target features belonging to a particular function. The form can be described in the following BNF form. 
-
-```
-FeatureString          := EXTENSIONS
-EXTENSIONS             := <EXTENSION-NAME> ';' <EXTENSIONS>
-                        | <EXTENSION-NAME>
-EXTENSION-NAME         := Naming rule is defined in RISC-V ISA manual
-```
-
-If all features are available for the current runtime environment, it returns true. Otherwise, it returns false.
+Function multi-versioning(FMV) provides an approach to selecting the appropriate function according to the runtime environment. This feature is triggered by `target_version/target_clones` function attribute.