OMAPDSS: add define for DRA7xx HW version

Add define for DRA7xx DSS version.
Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>

include/video/omapdss.h

@@ -314,6 +314,7 @@ enum omapdss_version {
 	OMAPDSS_VER_OMAP4,		/* All other OMAP4s */
 	OMAPDSS_VER_OMAP5,
 	OMAPDSS_VER_AM43xx,
+	OMAPDSS_VER_DRA7xx,
 };
 
 /* Board specific data */