drm: plane: Add plane options ioctl

drm: plane: Add plane options ioctl

Add a new ioctl DRM_IOCTL_MODE_PLANE_OPTS which is used to configure
various settings for the plane.

I left out gamma correction thinking that it could be added using a
separate ioctl, since there's already a gamma ioctl for CRTCs.

Signed-off-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Acked-by: Pauli Nieminen <pauli.nieminen@linux.intel.com>
Reviewed-by: Jani Nikula <jani.nikula@intel.com>
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>