[NFC]Update -fsplit-machine-functions now aarch64 function splitting is supported (#122860)

With https://reviews.llvm.org/D157157, mfs is supported on aarch64.

Author: mingmingl-llvm

clang/include/clang/Driver/Options.td

@@ -4364,7 +4364,7 @@ defm split_machine_functions: BoolFOption<"split-machine-functions",
   CodeGenOpts<"SplitMachineFunctions">, DefaultFalse,
   PosFlag<SetTrue, [], [ClangOption, CC1Option], "Enable">,
   NegFlag<SetFalse, [], [ClangOption], "Disable">,
-  BothFlags<[], [ClangOption], " late function splitting using profile information (x86 ELF)">>;
+  BothFlags<[], [ClangOption], " late function splitting using profile information (x86 and aarch64 ELF)">>;
 
 defm strict_return : BoolFOption<"strict-return",
   CodeGenOpts<"StrictReturn">, DefaultTrue,