[llvm] CSKY: Consume "float-abi" module flag (PR #212975)

[Matt Arsenault via llvm-commits]

arsenm wrote:

> Can we just abandon this patch or is the plan to phase out the function attribute / target option and we would need to make some changes to make the backend compilable anyway? 

I have the patches about ready to delete the TargetOptions field and only use the module flag / triple default; this is a bringup patch blocking that. The subtarget feature is untested and should be deleted 



https://github.com/llvm/llvm-project/pull/212975