netfilter: xt_CT: Remove redundant assignment to ret

Variable 'ret' is set to zero but this value is never read as it is
overwritten with a new value later on, hence it is a redundant
assignment and can be removed

Clean up the following clang-analyzer warning:

net/netfilter/xt_CT.c:175:2: warning: Value stored to 'ret' is never read [clang-analyzer-deadcode.DeadStores]
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Yang Li <yang.lee@linux.alibaba.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/xt_CT.c

@@ -172,7 +172,6 @@ static int xt_ct_tg_check(const struct xt_tgchk_param *par,
 		goto err2;
 	}
 
-	ret = 0;
 	if ((info->ct_events || info->exp_events) &&
 	    !nf_ct_ecache_ext_add(ct, info->ct_events, info->exp_events,
 				  GFP_KERNEL)) {