radv: use 3d shader for gfx9 copies if dst is 3d
This fixes some crucible 3d miptree tests I've been working on when executed using the compute shader path. Fixes: d08f2678 (radv/gfx9: fix 3d image to image transfers on compute queues.) Reviewed-by:Samuel Pitoiset <samuel.pitoiset@gmail.com> (cherry picked from commit 1363a47c)