radeonsi: disable SDMA on gfx6-7 and gfx10.3 to decrease CPU overhead

same as gfx8-10

Reviewed-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/7055>
1 file changed