drm: add new mga ids and types

From: Ian Romanick <idr@us.ibm.com>
Signed-off-by: Dave Airlie <airlied@linux.ie>
diff --git a/drivers/char/drm/mga_drm.h b/drivers/char/drm/mga_drm.h
index 521d445..4500e6e 100644
--- a/drivers/char/drm/mga_drm.h
+++ b/drivers/char/drm/mga_drm.h
@@ -73,7 +73,8 @@
 
 #define MGA_CARD_TYPE_G200	1
 #define MGA_CARD_TYPE_G400	2
-
+#define MGA_CARD_TYPE_G450	3       /* not currently used */
+#define MGA_CARD_TYPE_G550	4
 
 #define MGA_FRONT		0x1
 #define MGA_BACK		0x2