[llvm] [MIPS] Fix -msingle-float doesn't work with double on O32 (PR #107543)

[via llvm-commits]

yingopq wrote:

> > Ohh. Thanks. Your patch fixes this problem.
> > And I will approve this PR once you fix the problem Matt found. I guess he meant that you can just remove `N->getOpcode() == ISD::BITCAST`
> 
> I mean the entire thing is suspect, you can request custom lowering on illegal types so CustomLowerNode should never be skipped

OK, I would find another solution.

https://github.com/llvm/llvm-project/pull/107543