[AArch64] Fix scalar vuqadd intrinsics operands
Change the vuqadd scalar instrinsics to have the second argument as unsigned values, not signed,
accordingly to https://developer.arm.com/architectures/instruction-sets/simd-isas/neon/intrinsics
So now the compiler correctly warns that a undefined negative float conversion is being done.
Reviewers: LukeCheeseman, john.brawn
Reviewed By: john.brawn
Subscribers: john.brawn, javed.absar, kristof.beyls, cfe-commits
Differential Revision: https://reviews.llvm.org/D64242