[llvm] [AMDGPU][MC] Restrict op_sel in VOP3P dot instructions (PR #100485)

[Stanislav Mekhanoshin via llvm-commits]

rampitec wrote:

> @Sisyph @arsenm @rampitec So far two solutions have been tried: (1) disallow OPSEL for v_dot4_* and v_dot8_* for pre-GFX11 targets (2) allow OPSEL for all targets but its value must be 0. A 3rd option is not to make any fix and leave things as they are. Pls let me know your thoughts.

I would disallow it. Why pre-GFX11 only? It does not do anything for dot4 and dot8 on any target.

https://github.com/llvm/llvm-project/pull/100485