[AArch64] Fix abs(sub nsw) -> absd

This partially reverts a regression introduced in 8f25e382 for
AArch64 targets. In particular, we restore the logic of `(abs (sub nsw
x, y)) -> abds(x, y)` for all targets except X86, which keeps the logic
introduced in 8f25e382. See also https://reviews.llvm.org/D142288.

Differential Revision: https://reviews.llvm.org/D144379