sctp: fix unused lable warning

The proc file cleanup left a label possibly unused:

net/sctp/protocol.c: In function 'sctp_defaults_init':
net/sctp/protocol.c:1304:1: error: label 'err_init_proc' defined but not used [-Werror=unused-label]

This adds an #ifdef around it to match the respective 'goto'.

Fixes: d47d08c8 ("sctp: use proc_remove_subtree()")
Signed-off-by: NArnd Bergmann <arnd@arndb.de>
Acked-by: NNeil Horman <nhorman@tuxdriver.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/sctp/protocol.c

@@ -1258,8 +1258,10 @@ static int __net_init sctp_defaults_init(struct net *net)
 
 	return 0;
 
+#ifdef CONFIG_PROC_FS
 err_init_proc:
 	cleanup_sctp_mibs(net);
+#endif
 err_init_mibs:
 	sctp_sysctl_net_unregister(net);
 err_sysctl_register: