Add a function to create a standards compliant rotation property.
Signed-off-by: NVille Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: NImre Deak <imre.deak@intel.com>
Acked-by: NDave Airlie <airlied@linux.ie>
Signed-off-by: NDaniel Vetter <daniel.vetter@ffwll.ch>