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

[Ivan Kosarev via llvm-commits]

kosarev wrote:

> Can you give an example that llvm-objdump is insufficient for your case?

Using `llvm-objdump` would require having two separate check lines for every instruction, avoiding which is the point of the patch.

```
v_bfrev_b32_e32 v5, v1
// GFX12-ASM: v_bfrev_b32_e32 v5, v1                  ; encoding: [0x01,0x71,0x0a,0x7e]
// GFX12-DIS: v_bfrev_b32_e32 v5, v1                                     // 000000000000: 7E0A7101
```

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