drm/amd/display: skip crtc power down when ips switch

[Why & How]
Add a dc debug option to keep crtc on when ips switch.

Reviewed-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Signed-off-by: Fudong Wang <Fudong.Wang@amd.com>
Signed-off-by: Wayne Lin <wayne.lin@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>