snmp: fix some left over of snmp stats

Fengguang reported the following sparse warning:

>> net/ipv6/proc.c:198:41: sparse: incorrect type in argument 1 (different address spaces)
   net/ipv6/proc.c:198:41:    expected void [noderef] <asn:3>*mib
   net/ipv6/proc.c:198:41:    got void [noderef] <asn:3>**pcpumib

Fixes: commit 698365fa1874aa7635d51667a3 (net: clean up snmp stats code)
Reported-by: Fengguang Wu <fengguang.wu@intel.com>
Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/sctp/proc.c b/net/sctp/proc.c
index 0947f1e..34229ee 100644
--- a/net/sctp/proc.c
+++ b/net/sctp/proc.c
@@ -78,7 +78,7 @@
 
 	for (i = 0; sctp_snmp_list[i].name != NULL; i++)
 		seq_printf(seq, "%-32s\t%ld\n", sctp_snmp_list[i].name,
-			   snmp_fold_field((void __percpu **)net->sctp.sctp_statistics,
+			   snmp_fold_field(net->sctp.sctp_statistics,
 				      sctp_snmp_list[i].entry));
 
 	return 0;