staging: gdm724x: Use NLMSG_HDRLEN

Replace use of  NLMSG_SPACE(0) with NLMSG_HDRLEN as they are equivalent
and NLMSG_SPACE seems to be deprecated.
Signed-off-by: Himangi Saraogi <himangi774@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/gdm724x/netlink_k.c

@@ -54,7 +54,7 @@ static void netlink_rcv_cb(struct sk_buff *skb)
 		return;
 	}
 
-	if (skb->len < NLMSG_SPACE(0)) {
+	if (skb->len < NLMSG_HDRLEN) {
 		pr_err("nl cb - invalid skb length\n");
 		return;
 	}