Revert "can: fix handling of unmodifiable configuration options fix"

This reverts commit 6f8f768a which was
bce271f2 upstream.

It was applied incorrectly, and isn't needed for 3.14-stable.
Reported-by: Willy Tarreau <w@1wt.eu>
Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org

drivers/net/can/dev.c

@@ -665,9 +665,6 @@ static int can_changelink(struct net_device *dev,
 		}
 	}
 
-	if (!data)
-		return 0;
-
 	if (data[IFLA_CAN_CTRLMODE]) {
 		struct can_ctrlmode *cm;