[clang] [llvm] Revert "[X86][AVX10.2] Support YMM rounding new instructions (#101825)" (PR #132362)

[Simon Pilgrim via llvm-commits]

https://github.com/RKSimon approved this pull request.

LGTM - do we have to remove avx10-256 as well (and just use prefer vector width) or will that remain in some form?

https://github.com/llvm/llvm-project/pull/132362