[llvm] [NFC] Add useFPRegsForHalfType(). (PR #74147)

[Harald van Dijk via llvm-commits]

hvdijk wrote:

Follow-up: https://github.com/llvm/llvm-project/pull/80440. If that is approved and merged, I think I'll just create an issue and ask Tom Stellard's opinion on cherry-picking.

https://github.com/llvm/llvm-project/pull/74147