ipv6: rpl: Remove redundant multicast tests in ipv6_rpl_srh_rcv().

ipv6_rpl_srh_rcv() checks if ipv6_hdr(skb)->daddr or ohdr->rpl_segaddr[i]
is the multicast address with ipv6_addr_type().

We have the same check for ipv6_hdr(skb)->daddr in ipv6_rthdr_rcv(), so we
need not recheck it in ipv6_rpl_srh_rcv().

Also, we should use ipv6_addr_is_multicast() for ohdr->rpl_segaddr[i]
instead of ipv6_addr_type().

Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

net/ipv6/exthdrs.c

@@ -571,8 +571,7 @@ static int ipv6_rpl_srh_rcv(struct sk_buff *skb)
 	ipv6_rpl_srh_decompress(ohdr, hdr, &ipv6_hdr(skb)->daddr, n);
 	chdr = (struct ipv6_rpl_sr_hdr *)(buf + ((ohdr->hdrlen + 1) << 3));
 
-	if ((ipv6_addr_type(&ipv6_hdr(skb)->daddr) & IPV6_ADDR_MULTICAST) ||
-	    (ipv6_addr_type(&ohdr->rpl_segaddr[i]) & IPV6_ADDR_MULTICAST)) {
+	if (ipv6_addr_is_multicast(&ohdr->rpl_segaddr[i])) {
 		kfree_skb(skb);
 		kfree(buf);
 		return -1;