netfilter: rpfilter: Remove unused variable 'ret'.

Commit 91a17825 ("netfilter: rpfilter: Convert
rpfilter_lookup_reverse to new dev helper") removed the need for the
'ret' variable. This went unnoticed because of the __maybe_unused
annotation.
Signed-off-by: Guillaume Nault <gnault@redhat.com>
Signed-off-by: Florian Westphal <fw@strlen.de>

net/ipv4/netfilter/ipt_rpfilter.c

@@ -33,7 +33,6 @@ static bool rpfilter_lookup_reverse(struct net *net, struct flowi4 *fl4,
 				const struct net_device *dev, u8 flags)
 {
 	struct fib_result res;
-	int ret __maybe_unused;
 
 	if (fib_lookup(net, fl4, &res, FIB_LOOKUP_IGNORE_LINKSTATE))
 		return false;