In dce110, the plane configuration is such that plane 0
or the primary plane should be rendered with only RGB data.

This patch adds the validation to ensure that no video data
is rendered on plane 0.

Signed-off-by: Shirish S <shirish.s@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>