drm/amd/display: Use plane->color_space for dpp if specified

drm/amd/display: Use plane->color_space for dpp if specified

[Why]
The input color space for the plane was previously ignored even if it
was set.

If a limited range YUV format was given to DC then the
wrong color transformation matrix was being used since DC assumed that
it was full range instead.

[How]
Respect the given color_space format for the plane if it isn't
COLOR_SPACE_UNKNOWN. Otherwise, use the implicit default since DM
didn't specify.

Signed-off-by: Nicholas Kazlauskas <[email protected]>
Reviewed-by: Sun peng Li <[email protected]>
Acked-by: Aric Cyr <[email protected]>
Acked-by: Leo Li <[email protected]>
Signed-off-by: Alex Deucher <[email protected]>