drm/amd/display: add Cursor Degamma logic for DCN2

[Why]
We need to have the ability to to tell us set degamma on the cursor.

[How]
Pass a flag down to register programming that tells us if the
current surface format needs cursor degamma.

Signed-off-by: Bayan Zabihiyan <bayan.zabihiyan@amd.com>
Reviewed-by: Krunoslav Kovac <Krunoslav.Kovac@amd.com>
Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>