[llvm] [WIP][AMDGPU][MC] Allow 128-bit rsrc register in MIMG instructions (PR #132264)

[Jay Foad via llvm-commits]

jayfoad wrote:

> So, if I continue with the approach I'd have to modify the class `MCInstrDesc`.

That's #138127, right?

https://github.com/llvm/llvm-project/pull/132264