[llvm] [AMDGPU][RFC] Combine asm and disasm tests. (PR #90214)

[Ivan Kosarev via llvm-commits]

kosarev wrote:

@MaskRay `llvm-objdump -d` doesn't use the asm streamer, meaning it would require separate check lines, whereas the idea is to make same check lines work for both the assembler and disassembler tests.

Regarding round-tripping, we may want to consider that at some point, but we still need to directly check what the disassembler produces, because reassembling may mask problems.

https://github.com/llvm/llvm-project/pull/90214