[clang] [Clang][RISCV] Remove duplicate functions isRVVSizelessBuiltinType. NFC (PR #67089)

[Craig Topper via cfe-commits]

topperc wrote:

> Can we reverse this patch? Keep isRVVSizelessBuiltinType and remove isRVVType. The implementation of isRVVSizelessBuiltinType is more efficient according to some profiling. At least on Release+Asserts build

I went ahead and committed that change.

https://github.com/llvm/llvm-project/pull/67089