sunrpc: use the struct net as the svc proc private

nfsd is the only thing using this helper, and it doesn't use the private
currently.  When we switch to per-network namespace stats we will need
the struct net * in order to get to the nfsd_net.  Use the net as the
proc private so we can utilize this when we make the switch over.
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

net/sunrpc/stats.c

@@ -314,7 +314,7 @@ EXPORT_SYMBOL_GPL(rpc_proc_unregister);
 struct proc_dir_entry *
 svc_proc_register(struct net *net, struct svc_stat *statp, const struct proc_ops *proc_ops)
 {
-	return do_register(net, statp->program->pg_name, statp, proc_ops);
+	return do_register(net, statp->program->pg_name, net, proc_ops);
 }
 EXPORT_SYMBOL_GPL(svc_proc_register);