[llvm] [X86][SchedModel] Add masked gather/scatter overrides to Znver4Model (PR #212997)

[Simon Pilgrim via llvm-commits]

https://github.com/RKSimon commented:

Please can you rewrite the patch summary - its incredibly difficult to grok, and not helpful at all. Same with a lot of the comments you've added to the model - bulky and not helpful.

https://github.com/llvm/llvm-project/pull/212997