drm/radeon: hard reset r600 and newer GPU when hibernating.

Some GPU block like UVD and VCE require hard reset to be properly
resume if there is no real powerdown of the asic like during various
hibernation step. This patch perform such hard reset.

Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Jérôme Glisse <jglisse@redhat.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>