net/caif/caif_socket.c: remove unnecessary null test before debugfs_remove_recursive

based on checkpatch:
"debugfs_remove_recursive(NULL) is safe this check is probably not required"

Cc: Dmitry Tarnyagin <dmitry.tarnyagin@lockless.no>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: netdev@vger.kernel.org
Signed-off-by: NFabian Frederick <fabf@skynet.be>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/caif/caif_socket.c

@@ -908,8 +908,7 @@ static int caif_release(struct socket *sock)
 	sock->sk = NULL;
 
 	WARN_ON(IS_ERR(cf_sk->debugfs_socket_dir));
-	if (cf_sk->debugfs_socket_dir != NULL)
-		debugfs_remove_recursive(cf_sk->debugfs_socket_dir);
+	debugfs_remove_recursive(cf_sk->debugfs_socket_dir);
 
 	lock_sock(&(cf_sk->sk));
 	sk->sk_state = CAIF_DISCONNECTED;