[LoongArch][Clang] Make the parameters and return value of {x,}vshuf.b builtins `signed char` vectors#114512

SixWeining merged 1 commit intollvm:mainllvm/llvm-project:mainfrom

xry111:xry111/fix-110834-04-shufxry111/llvm-project:xry111/fix-110834-04-shufCopy head branch name to clipboard