ipv6 Use get_hash_from_flowi6 for rt6 hash

In rt6_info_hash_nhsfn replace the custom hashing over flowi6 that is
using xor with a call to common function get_hash_from_flowi6.
Signed-off-by: Tom Herbert <tom@herbertland.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/route.c

@@ -421,31 +421,7 @@ static bool rt6_check_expired(const struct rt6_info *rt)
 static int rt6_info_hash_nhsfn(unsigned int candidate_count,
 			       const struct flowi6 *fl6)
 {
-	unsigned int val = fl6->flowi6_proto;
-
-	val ^= ipv6_addr_hash(&fl6->daddr);
-	val ^= ipv6_addr_hash(&fl6->saddr);
-
-	/* Work only if this not encapsulated */
-	switch (fl6->flowi6_proto) {
-	case IPPROTO_UDP:
-	case IPPROTO_TCP:
-	case IPPROTO_SCTP:
-		val ^= (__force u16)fl6->fl6_sport;
-		val ^= (__force u16)fl6->fl6_dport;
-		break;
-
-	case IPPROTO_ICMPV6:
-		val ^= (__force u16)fl6->fl6_icmp_type;
-		val ^= (__force u16)fl6->fl6_icmp_code;
-		break;
-	}
-	/* RFC6438 recommands to use flowlabel */
-	val ^= (__force u32)fl6->flowlabel;
-
-	/* Perhaps, we need to tune, this function? */
-	val = val ^ (val >> 7) ^ (val >> 12);
-	return val % candidate_count;
+	return get_hash_from_flowi6(fl6) % candidate_count;
 }
 
 static struct rt6_info *rt6_multipath_select(struct rt6_info *match,