[AArch64] Add lowering pattern for scalar fp16 facge and facgt
Summary: The fp16 scalar version of facge and facgt requires a custom patter matching, as the result type is not the same width of the operands.
Reviewers: olista01, javed.absar, pbarrio
Reviewed By: javed.absar
Subscribers: kristof.beyls, llvm-commits
Differential Revision: https://reviews.llvm.org/D60212