drm/amd/display: Fix BUG_ON during CRTC atomic check update

For cases where the CRTC is inactive (DPMS off), where a modeset is not
required, yet the CRTC is still in the atomic state, we should not
attempt to update anything on it.

Previously, we were relying on the modereset_required() helper to check
the above condition. However, the function returns false immediately if
a modeset is not required, ignoring the CRTC's enable/active state
flags. The correct way to filter is by looking at these flags instead.

Fixes: e277adc5

 "drm/amd/display: Hookup color management functions"
Bugzilla: https://bugs.freedesktop.org/106194

Signed-off-by: Leo (Sunpeng) Li <sunpeng.li@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Tested-by: Michel Dänzer <michel.daenzer@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>