drm: Turn DRM_MODE_SUBCONNECTOR_xx definitions into an enum

List of values like the DRM_MODE_SUBCONNECTOR_xx ones are better
represented with enums.

Turn the DRM_MODE_SUBCONNECTOR_xx macros into an enum.
Signed-off-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Suggested-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Signed-off-by: Eric Anholt <eric@anholt.net>

include/uapi/drm/drm_mode.h

@@ -220,14 +220,16 @@ struct drm_mode_get_encoder {
 
 /* This is for connectors with multiple signal types. */
 /* Try to match DRM_MODE_CONNECTOR_X as closely as possible. */
-#define DRM_MODE_SUBCONNECTOR_Automatic	0
-#define DRM_MODE_SUBCONNECTOR_Unknown	0
-#define DRM_MODE_SUBCONNECTOR_DVID	3
-#define DRM_MODE_SUBCONNECTOR_DVIA	4
-#define DRM_MODE_SUBCONNECTOR_Composite	5
-#define DRM_MODE_SUBCONNECTOR_SVIDEO	6
-#define DRM_MODE_SUBCONNECTOR_Component	8
-#define DRM_MODE_SUBCONNECTOR_SCART	9
+enum drm_mode_subconnector {
+	DRM_MODE_SUBCONNECTOR_Automatic = 0,
+	DRM_MODE_SUBCONNECTOR_Unknown = 0,
+	DRM_MODE_SUBCONNECTOR_DVID = 3,
+	DRM_MODE_SUBCONNECTOR_DVIA = 4,
+	DRM_MODE_SUBCONNECTOR_Composite = 5,
+	DRM_MODE_SUBCONNECTOR_SVIDEO = 6,
+	DRM_MODE_SUBCONNECTOR_Component = 8,
+	DRM_MODE_SUBCONNECTOR_SCART = 9,
+};
 
 #define DRM_MODE_CONNECTOR_Unknown	0
 #define DRM_MODE_CONNECTOR_VGA		1