net: socket: Fix missing break in switch statement

Add missing break statement in order to prevent the code from falling
through to cases SIOCGSTAMP_NEW and SIOCGSTAMPNS_NEW.

This bug was found thanks to the ongoing efforts to enable
-Wimplicit-fallthrough.

Fixes: 0768e170 ("net: socket: implement 64-bit timestamps")
Signed-off-by: Gustavo A. R. Silva <gustavo@embeddedor.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/socket.c

@@ -1173,6 +1173,7 @@ static long sock_ioctl(struct file *file, unsigned cmd, unsigned long arg)
 			err = sock->ops->gettstamp(sock, argp,
 						   cmd == SIOCGSTAMP_OLD,
 						   !IS_ENABLED(CONFIG_64BIT));
+			break;
 		case SIOCGSTAMP_NEW:
 		case SIOCGSTAMPNS_NEW:
 			if (!sock->ops->gettstamp) {