[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_transport_iscsi.c b/drivers/scsi/scsi_transport_iscsi.c
index ef0e742..0d7b4e7 100644
--- a/drivers/scsi/scsi_transport_iscsi.c
+++ b/drivers/scsi/scsi_transport_iscsi.c
@@ -1558,7 +1558,7 @@
 	return 0;
 
 release_nls:
-	sock_release(nls->sk_socket);
+	netlink_kernel_release(nls);
 unregister_session_class:
 	transport_class_unregister(&iscsi_session_class);
 unregister_conn_class:
@@ -1573,7 +1573,7 @@
 static void __exit iscsi_transport_exit(void)
 {
 	destroy_workqueue(iscsi_eh_timer_workq);
-	sock_release(nls->sk_socket);
+	netlink_kernel_release(nls);
 	transport_class_unregister(&iscsi_connection_class);
 	transport_class_unregister(&iscsi_session_class);
 	transport_class_unregister(&iscsi_host_class);