drm/amd/display: Add extra check for 444 16 format

DCN30 is missing a check for the pixel format 444 when using 16bits
before setting the flag that Viewport exceeds the surface.

Reviewed-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>