radeonsi: fix si_compute_copy_image if DCC decompression happens before a copy
The buffer clear after DCC decompression overwrote user SGPRs that we set here, leading to invalid image coordinates. Set them after we bind images.
This will actually be fixed by "radeonsi: don't decompress DCC for float formats in si_compute_copy_image" as well.
Fixes: ad71ef93 "radeonsi: don't use a constant buffer for the copy_image compute shader"