netfilter: nf_tables: fix a wrong check to skip the inactive rules

nft_genmask_cur has already done left-shift operator on the gencursor,
so there's no need to do left-shift operator on it again.

Fixes: ea4bd995b0f2 ("netfilter: nf_tables: add transaction helper functions")
Cc: Patrick McHardy <kaber@trash.net>
Signed-off-by: Liping Zhang <liping.zhang@spreadtrum.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nf_tables_core.c

@@ -143,7 +143,7 @@ next_rule:
 	list_for_each_entry_continue_rcu(rule, &chain->rules, list) {
 
 		/* This rule is not active, skip. */
-		if (unlikely(rule->genmask & (1 << gencursor)))
+		if (unlikely(rule->genmask & gencursor))
 			continue;
 
 		rulenum++;