[NETNS]: Consolidate kernel netlink socket destruction.

Create a specific helper for netlink kernel socket disposal. This just
let the code look better and provides a ground for proper disposal
inside a namespace.

Signed-off-by: Denis V. Lunev <den@openvz.org>
Tested-by: Alexey Dobriyan <adobriyan@openvz.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/scsi/scsi_netlink.c b/drivers/scsi/scsi_netlink.c
index 3e15918..370c78c 100644
--- a/drivers/scsi/scsi_netlink.c
+++ b/drivers/scsi/scsi_netlink.c
@@ -164,7 +164,7 @@
 scsi_netlink_exit(void)
 {
 	if (scsi_nl_sock) {
-		sock_release(scsi_nl_sock->sk_socket);
+		netlink_kernel_release(scsi_nl_sock);
 		netlink_unregister_notifier(&scsi_netlink_notifier);
 	}