[AMDGPU] Implement CFI for non-kernel functions
This does not implement CSR spills other than those AMDGPU handles
during PEI. The remaining spills are handled in a subsequent patch.
Co-authored-by: Scott Linder <scott.linder@amd.com>
Co-authored-by: Venkata Ramanaiah Nalamothu <VenkataRamanaiah.Nalamothu@amd.com>
