[llvm] [AMDGPU][MC][True16] Rename and combine VINTERP MC tests (PR #85949)

[Ivan Kosarev via llvm-commits]

https://github.com/kosarev approved this pull request.

I understand the instruction is:
```
v_interp_p10_f32 v0, v1, v2, v3 wait_exp:0  // 000000000000: CD800000 1C0E0501
v_interp_p10_f32 v0, v1, v2, v3 wait_exp:0  // 000000000000: CDE00000 1C0E0501
```
The bits 21 and 22 are not used on GFX12 and the test case in `gfx12_dasm_vinterp.txt` makes it clear that we test them raised intentionally:
```
# Check that unused bits in the encoding are ignored.
# CHECK: v_interp_p10_f32 v0, v1, v2, v3 wait_exp:0{{$}}
0x00,0x00,0xe0,0xcd,0x01,0x05,0x0e,0x1c
```
So technically this is a regression in coverage, but combining the tests is still very appealing,  so still LGTM.

Maybe we can test it somewhere for GFX12 specifically?

https://github.com/llvm/llvm-project/pull/85949