drm/amd/display: Separate caps for maximum RGB and YUV plane counts

Not all ASICs have same plane capabilities so need to split them
out for proper support handling.

Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Atufa Khan <Atufa.Khan@amd.com>
Reviewed-by: Aric Cyr <Aric.Cyr@amd.com>
Acked-by: Solomon Chiu <solomon.chiu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>