[AArch64] Fix incorrect getSetCCInverse usage within trySwapVSelectOperands.

When inverting the compare predicate trySwapVSelectOperands is
incorrectly using the type of the select's cond operand rather
than the type of cond's operands. This means we're treating all
inversions as if they're integer.

Differential Revision: https://reviews.llvm.org/D121968