drm/amd/display: Remove unnecessary DSC power gating for DCN401

drm/amd/display: Remove unnecessary DSC power gating for DCN401

[Why]
In some cases during topology changes, a pipe that was used to drive a
stream being removed can be re-assigned to drive a different stream. In
these cases, DSC power gating is not handled properly, leading to
situations where DSC is being setup while power gated.

[How]
 - remove enable_stream_gating and disable_stream_gating for DCN401

Reviewed-by: Wenjing Liu <wenjing.liu@amd.com>
Signed-off-by: Jerry Zuo <jerry.zuo@amd.com>
Signed-off-by: Joshua Aberback <joshua.aberback@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>