atm: fix info leak via getsockname()

The ATM code fails to initialize the two padding bytes of struct
sockaddr_atmpvc inserted for alignment. Add an explicit memset(0)
before filling the structure to avoid the info leak.

Signed-off-by: Mathias Krause <minipli@googlemail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
static int pvc_getsockopt(struct socket *sock, int level, int optname,
			  char __user *optval, int __user *optlen)
{
	struct sock *sk = sock->sk;
	int error;

	lock_sock(sk);
	error = vcc_getsockopt(sock, level, optname, optval, optlen);
	release_sock(sk);
	return error;
}

static int pvc_getsockopt(struct socket *sock, int level, int optname,
			  char __user *optval, int __user *optlen)
{
	struct sock *sk = sock->sk;
	int error;

	lock_sock(sk);
	error = vcc_getsockopt(sock, level, optname, optval, optlen);
	release_sock(sk);
	return error;
}
