video: fbdev: fix possible null dereference

we were dereferencing edid first and the NULL check was after
accessing that. now we are using edid only if we know that
it is not NULL.
Signed-off-by: NSudip Mukherjee <sudip@vectorindia.org>
Signed-off-by: NTomi Valkeinen <tomi.valkeinen@ti.com>

drivers/video/fbdev/core/fbmon.c

@@ -624,9 +624,6 @@ static struct fb_videomode *fb_create_modedb(unsigned char *edid, int *dbsize,
 	int num = 0, i, first = 1;
 	int ver, rev;
 
-	ver = edid[EDID_STRUCT_VERSION];
-	rev = edid[EDID_STRUCT_REVISION];
-
 	mode = kzalloc(50 * sizeof(struct fb_videomode), GFP_KERNEL);
 	if (mode == NULL)
 		return NULL;
@@ -637,6 +634,9 @@ static struct fb_videomode *fb_create_modedb(unsigned char *edid, int *dbsize,
 		return NULL;
 	}
 
+	ver = edid[EDID_STRUCT_VERSION];
+	rev = edid[EDID_STRUCT_REVISION];
+
 	*dbsize = 0;
 
 	DPRINTK("   Detailed Timings\n");