atm: sk_wmem_alloc initial value is one

commit 2b85a34e911bf483c27cfdd124aeb1605145dc80
(net: No more expensive sock_hold()/sock_put() on each tx)
changed initial sk_wmem_alloc value.

This broke net/atm since this protocol assumed a null
initial value. This patch makes necessary changes.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/atm/ioctl.c b/net/atm/ioctl.c
index 76ed3c8..4da8892 100644
--- a/net/atm/ioctl.c
+++ b/net/atm/ioctl.c
@@ -63,8 +63,7 @@
 				error =  -EINVAL;
 				goto done;
 			}
-			error = put_user(sk->sk_sndbuf -
-					 atomic_read(&sk->sk_wmem_alloc),
+			error = put_user(sk->sk_sndbuf - sk_wmem_alloc_get(sk),
 					 (int __user *) argp) ? -EFAULT : 0;
 			goto done;
 		case SIOCINQ: