[llvm] [RISC-V] Fix crash with late stack realignment requirement (PR #83496)

[Nemanja Ivanovic via llvm-commits]

https://github.com/nemanjai commented:

Another possible solution would be to change the alignment requirement for `GPRPair` to 32. Perhaps this would need to only be done when the E extension is enabled, so maybe it would require a separate register class.
In any case, thought I'd propose these suggestions and we can converge on some solution to this problem.

https://github.com/llvm/llvm-project/pull/83496