OMAPDSS: add define for DRA7xx HW version

Add define for DRA7xx DSS version.

Signed-off-by: Tomi Valkeinen <tomi.valkeinen@ti.com>
diff --git a/include/video/omapdss.h b/include/video/omapdss.h
index 6a84498..60de61f 100644
--- a/include/video/omapdss.h
+++ b/include/video/omapdss.h
@@ -314,6 +314,7 @@
 	OMAPDSS_VER_OMAP4,		/* All other OMAP4s */
 	OMAPDSS_VER_OMAP5,
 	OMAPDSS_VER_AM43xx,
+	OMAPDSS_VER_DRA7xx,
 };
 
 /* Board specific data */