netfilter: xtables: use ipt_get_target_c instead of ipt_get_target

ipt_get_target is used to get struct xt_entry_target
and ipt_get_target_c is used to get const struct xt_entry_target.
However in the ipt_do_table, ipt_get_target is used to get
const struct xt_entry_target. it should be replaced by ipt_get_target_c.
Signed-off-by: NTaehee Yoo <ap420073@gmail.com>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

net/ipv4/netfilter/ip_tables.c

@@ -300,7 +300,7 @@ ipt_do_table(struct sk_buff *skb,
 		counter = xt_get_this_cpu_counter(&e->counters);
 		ADD_COUNTER(*counter, skb->len, 1);
 
-		t = ipt_get_target(e);
+		t = ipt_get_target_c(e);
 		WARN_ON(!t->u.kernel.target);
 
 #if IS_ENABLED(CONFIG_NETFILTER_XT_TARGET_TRACE)