[NFC][AArch64] Fix vector vqtb[lx][1-4]_s8 operand

Summary:
Change the vqtb[lx][1-4]_s8 instrinsics to have the last argument as vector of unsigned valuse, not
signed, accordingly to https://developer.arm.com/architectures/instruction-sets/simd-isas/neon/intrinsics

Reviewers: LukeCheeseman, DavidSpickett

Reviewed By: DavidSpickett

Subscribers: DavidSpickett, javed.absar, kristof.beyls, cfe-commits

Tags: #clang

Differential Revision: https://reviews.llvm.org/D64243

llvm-svn: 365598