netfilter: ctnetlink: do not erase error code with EINVAL

And be consistent in error management for both orig/reply filtering

Fixes: cb8aa9a ("netfilter: ctnetlink: add kernel side filtering for dump")
Signed-off-by: Florent Fourcot <florent.fourcot@wifirst.fr>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nf_conntrack_netlink.c

@@ -1012,10 +1012,8 @@ ctnetlink_alloc_filter(const struct nlattr * const cda[], u8 family)
 						   filter->family,
 						   &filter->zone,
 						   filter->reply_flags);
-		if (err < 0) {
-			err = -EINVAL;
+		if (err < 0)
 			goto err_filter;
-		}
 	}
 
 	return filter;