[NETFILTER]: nf_nat_snmp: sparse warning

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv4/netfilter/nf_nat_snmp_basic.c

@@ -260,7 +260,7 @@ static unsigned char asn1_eoc_decode(struct asn1_ctx *ctx, unsigned char *eoc)
 {
 	unsigned char ch;
 
-	if (eoc == 0) {
+	if (eoc == NULL) {
 		if (!asn1_octet_decode(ctx, &ch))
 			return 0;