[llvm] [AMDGPU][MC] Support src modifiers for v_mov_b32 and v_movrel* instructions (PR #76498)

[Matt Arsenault via llvm-commits]

arsenm wrote:

Real bot failure:

```
Failed Tests (5):
  LLVM :: MC/Disassembler/AMDGPU/gfx10_vop1.txt
  LLVM :: MC/Disassembler/AMDGPU/gfx11_dasm_vop1.txt
  LLVM :: MC/Disassembler/AMDGPU/gfx11_dasm_vop3_dpp16_from_vop1.txt
  LLVM :: MC/Disassembler/AMDGPU/gfx11_dasm_vop3_dpp8_from_vop1.txt
  LLVM :: MC/Disassembler/AMDGPU/gfx12_dasm_vop1.txt
```

https://github.com/llvm/llvm-project/pull/76498