[llvm] [AMDGPU][True16][MC] Support v_swap_b16. (PR #100442)

[Brox Chen via llvm-commits]

broxigarchen wrote:

> Can you please commit a separate patch first that contains the changes to llvm/test/MC/AMDGPU/gfx12_asm_vop1-fake16.s and llvm/test/MC/AMDGPU/gfx12_asm_vop1.s minus v_swap_b16? The files look fine, just adding that bulk test update should be separate from the functional change to v_swap_b16.

Created a seperate PR here https://github.com/llvm/llvm-project/pull/100849

https://github.com/llvm/llvm-project/pull/100442