[llvm] [llvm] Adopt WithMarkup in the MIPS backend (PR #65384)

[Daniel Sanders via llvm-commits]

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

LGTM but as noted the WithMarkup bit isn't very clear. I think that'd be better being explicit markup()'s just like the rest

https://github.com/llvm/llvm-project/pull/65384