drm/amd/display: Gamut remap only changes missed

drm/amd/display: Gamut remap only changes missed

[WHY&HOW]
If surface format is dynamically changed within app without changing
timing / whole plane, we don't reprogram gamut remap matrix.

Issue example:
Linear FP16 scRGB going to PQ+BT.2020 monitor.
Remap = scRGB->BT.2020

App switches swapchain format to 10-bit PQ+BT.2020.
SW calculates correctly that new Remap = bypass (in=-out=BT.2020).
But update not applied in HW.

Reviewed-by: Jun Lei <jun.lei@amd.com>
Acked-by: Stylon Wang <stylon.wang@amd.com>
Signed-off-by: Krunoslav Kovac <krunoslav.kovac@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>