[llvm] [MIPS] Fix wrong errors being emitted when rejecting certain assembly… (PR #94695)

[Jesse D via llvm-commits]

jdeguire wrote:

> Can we give a more detailed error, such as what feature is not set?

It looks like some other targets do this, so I should be able to add that to MIPS, too. Should something like that be a part of this PR or a later one?

https://github.com/llvm/llvm-project/pull/94695