[AMDGPU] Set implicit arg attributes for indirect calls
This patch adds attributes corresponding to
implicits to functions/kernels if
- it has an indirect call OR
- it's address is taken.
Once such attributes are set, rest of the codegen would work
out-of-box for indirect calls. This patch eliminates
the potential overhead -fixed-abi imposes even though indirect functions
calls are not used.
Reviewed By: arsenm
Differential Revision: https://reviews.llvm.org/D99347