[WHY]
HW has handed down a new sequence that requires access to these
registers.

v2: squash in DCN3.1 fixes (Alex)
Signed-off-by: NWesley Chalmers <Wesley.Chalmers@amd.com>
Reviewed-by: NDmytro Laktyushkin <Dmytro.Laktyushkin@amd.com>
Acked-by: NStylon Wang <stylon.wang@amd.com>
Tested-by: NDaniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: NAlex Deucher <alexander.deucher@amd.com>