[NETFILTER]: Fix check whether dst_entry needs to be released after NAT

After DNAT the original dst_entry needs to be released if present
so the packet doesn't skip input routing with its new address. The
current check for DNAT in ip_nat_in is reversed and checks for SNAT.
Signed-off-by: NPatrick McHardy <kaber@trash.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/netfilter/ip_nat_standalone.c

@@ -209,8 +209,8 @@ ip_nat_in(unsigned int hooknum,
 	    && (ct = ip_conntrack_get(*pskb, &ctinfo)) != NULL) {
 		enum ip_conntrack_dir dir = CTINFO2DIR(ctinfo);
 
-		if (ct->tuplehash[dir].tuple.src.ip !=
-		    ct->tuplehash[!dir].tuple.dst.ip) {
+		if (ct->tuplehash[dir].tuple.dst.ip !=
+		    ct->tuplehash[!dir].tuple.src.ip) {
 			dst_release((*pskb)->dst);
 			(*pskb)->dst = NULL;
 		}