[llvm] [TLI] Add basic support for fdim libcall (PR #108702)

[via llvm-commits]

braw-lee wrote:

@arsenm 
https://github.com/llvm/llvm-project/commit/43c9203d4946b7911d2ba69369717979900d7bc2
looks like this commit incremented the total TLI in ps4-tli-check.yaml to 253, so my commit of fdim should increment to 256
should this be handled in a new PR?

https://github.com/llvm/llvm-project/pull/108702