[2/3][Clang][RISCV] Add __riscv_ for non-overloaded intrinsics

This commit adds prefix for the non-overloaded RVV intrinsics.

This is the 2nd commit of a patch-set to add __riscv_ for all RVV
intrinsics.

This follows the naming guideline under riscv-c-api-doc to add the
`__riscv_` suffix for all RVV intrinsics.

Pull Request:
riscv-non-isa/riscv-c-api-doc#31
riscv-non-isa/rvv-intrinsic-doc#189

Depends on D142085.

Reviewed By: kito-cheng

Differential Revision: https://reviews.llvm.org/D142644

Author: eopXD

clang/lib/Support/RISCVVIntrinsicUtils.cpp

@@ -1002,6 +1002,10 @@ void RVVIntrinsic::updateNamesAndPolicy(bool IsMasked, bool HasPolicy,
     OverloadedName += suffix;
   };
 
+  // This follows the naming guideline under riscv-c-api-doc to add the
+  // `__riscv_` suffix for all RVV intrinsics.
+  Name = "__riscv_" + Name;
+
   if (IsMasked) {
     if (PolicyAttrs.isTUMUPolicy())
       appendPolicySuffix("_tumu");