radeonsi: disable SDMA image copies on dGPUs to fix corruption in games

Cc: 19.1 19.2 <mesa-stable@lists.freedesktop.org>
Reviewed-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
(cherry picked from commit 6b3ee869)
[Juan A. Suarez: resolve trivial conflicts]
Signed-off-by: Juan A. Suarez Romero <jasuarez@igalia.com>

Conflicts:
	src/gallium/drivers/radeonsi/cik_sdma.c