net: ipv6: more places need LOOPBACK_IFINDEX for flowi6_iif

To properly match iif in ip rules we have to provide
LOOPBACK_IFINDEX in flowi6_iif, not 0. Some ip6mr_fib_lookup
and fib6_rule_lookup callers need such fix.

Signed-off-by: Julian Anastasov <ja@ssi.bg>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/netfilter/ip6t_rpfilter.c b/net/ipv6/netfilter/ip6t_rpfilter.c
index e0983f3..790e0c6 100644
--- a/net/ipv6/netfilter/ip6t_rpfilter.c
+++ b/net/ipv6/netfilter/ip6t_rpfilter.c
@@ -33,6 +33,7 @@
 	struct ipv6hdr *iph = ipv6_hdr(skb);
 	bool ret = false;
 	struct flowi6 fl6 = {
+		.flowi6_iif = LOOPBACK_IFINDEX,
 		.flowlabel = (* (__be32 *) iph) & IPV6_FLOWINFO_MASK,
 		.flowi6_proto = iph->nexthdr,
 		.daddr = iph->saddr,