[llvm] [AMDGPU] Fix handling of FP in cs.chain functions (PR #161194)

[Robert Imschweiler via llvm-commits]

ro-i wrote:

@arsenm do you have any further comments?
I think the fix is correct since we don't need the FP in a chain function just because we "trivially require" the SP.
And modifying `frameTriviallyRequiresSP` doesn't seem right since it's also called in `SIFrameLowering::requiresStackPointerReference`, which probably should not be changed. That's why I think that I added the additional check in the right place.

https://github.com/llvm/llvm-project/pull/161194