IPVS: Add IPv6 support to SH and DH schedulers

Add IPv6 support to SH and DH schedulers. I hope this simple IPv6 address
hashing is good enough. The 128 bit are just XORed into 32 before hashing
them like an IPv4 address.

Signed-off-by: Julius Volz <julius.volz@gmail.com>
Acked-by: Simon Horman <horms@verge.net.au>
Signed-off-by: David S. Miller <davem@davemloft.net>