drm/amd/display: Fix black screen on video playback with embedded panel

[why]
We have dynamic power control in driver but
should be ignored when power is forced on.

[how]
Bypass any power control when it's forced on.

Cc: stable@vger.kernel.org
Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Acked-by: Hamza Mahfooz <hamza.mahfooz@amd.com>
Signed-off-by: Sung Joon Kim <sungkim@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>