[RISCV] Replace arm64 with riscv64 (#96889)

Co-authored-by: magus <[email protected]>

Author: minxuanz

src/coreclr/vm/riscv64/stubs.cpp

@@ -4,7 +4,7 @@
 // File: stubs.cpp
 //
 // This file contains stub functions for unimplemented features need to
-// run on the ARM64 platform.
+// run on the RISCV64 platform.
 
 #include "common.h"
 #include "dllimportcallback.h"
@@ -985,7 +985,7 @@ LONG CLRNoCatchHandler(EXCEPTION_POINTERS* pExceptionInfo, PVOID pv)
 
 void FlushWriteBarrierInstructionCache()
 {
-    // this wouldn't be called in arm64, just to comply with gchelpers.h
+    // this wouldn't be called in riscv64, just to comply with gchelpers.h
 }
 
 int StompWriteBarrierEphemeral(bool isRuntimeSuspended)

src/coreclr/vm/riscv64/virtualcallstubcpu.hpp

@@ -3,8 +3,8 @@
 //
 // VirtualCallStubCpu.hpp
 //
-#ifndef _VIRTUAL_CALL_STUB_ARM_H
-#define _VIRTUAL_CALL_STUB_ARM_H
+#ifndef _VIRTUAL_CALL_STUB_RISCV64_H
+#define _VIRTUAL_CALL_STUB_RISCV64_H
 
 #define DISPATCH_STUB_FIRST_DWORD 0x00000e97
 #define RESOLVE_STUB_FIRST_DWORD 0x00053e03
@@ -513,4 +513,4 @@ void VTableCallHolder::Initialize(unsigned slot)
 
 #endif //DECLARE_DATA
 
-#endif // _VIRTUAL_CALL_STUB_ARM_H
+#endif // _VIRTUAL_CALL_STUB_RISCV64_H