[llvm] [AMDGPU] Enable WMMA256bInsts + Wave32 for gfx1200/gfx1201 + SISchedule fix + TargetParser gfx1200 propagation (PR #202093)

[Alexandra Munkes via llvm-commits]

Malexandra-de wrote:

@clearnature Specifying `FeatureWavefrontSize32` is counterproductive, since there has recently been a refactor for this feature flag  #176599 . Whenever either `FeatureWavefrontSize64` or `FeatureWavefrontSize32` it now indicates that the target **exclusively** supports only that wavefront size.

https://github.com/llvm/llvm-project/pull/202093