[libclc] [libclc] Fix typo in __clc_atomic_dec/inc functions (PR #168327)

[Matt Arsenault via cfe-commits]

https://github.com/arsenm approved this pull request.

I think __clc_atomic_inc/dec should be deleted, or renamed. inc is a different op (i.e., atomicrmw uinc_wrap)

https://github.com/llvm/llvm-project/pull/168327