[NETLINK]: Don't leak 'listeners' in netlink_kernel_create()

The Coverity checker spotted that we'll leak the storage allocated
to 'listeners' in netlink_kernel_create() when the
  if (!nl_table[unit].registered)
check is false.

This patch avoids the leak.
Signed-off-by: Jesper Juhl <jesper.juhl@gmail.com>
Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/netlink/af_netlink.c

@@ -1378,6 +1378,8 @@ netlink_kernel_create(struct net *net, int unit, unsigned int groups,
 		nl_table[unit].cb_mutex = cb_mutex;
 		nl_table[unit].module = module;
 		nl_table[unit].registered = 1;
+	} else {
+		kfree(listeners);
 	}
 	netlink_table_ungrab();