drm/imx: enable ARGB4444 16-bit color format

This patch allows to use the ARGB4444 color format on planes.

Signed-off-by: Lucas Stach <l.stach@pengutronix.de>
Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
diff --git a/drivers/gpu/drm/imx/ipuv3-plane.c b/drivers/gpu/drm/imx/ipuv3-plane.c
index d030990..575f4c8 100644
--- a/drivers/gpu/drm/imx/ipuv3-plane.c
+++ b/drivers/gpu/drm/imx/ipuv3-plane.c
@@ -29,6 +29,7 @@
 	DRM_FORMAT_XBGR1555,
 	DRM_FORMAT_RGBA5551,
 	DRM_FORMAT_BGRA5551,
+	DRM_FORMAT_ARGB4444,
 	DRM_FORMAT_ARGB8888,
 	DRM_FORMAT_XRGB8888,
 	DRM_FORMAT_ABGR8888,
@@ -187,6 +188,7 @@
 		case DRM_FORMAT_ABGR1555:
 		case DRM_FORMAT_RGBA5551:
 		case DRM_FORMAT_BGRA5551:
+		case DRM_FORMAT_ARGB4444:
 		case DRM_FORMAT_ARGB8888:
 		case DRM_FORMAT_ABGR8888:
 		case DRM_FORMAT_RGBA8888: