net/ipv6: Add support for path selection using hash of 5-tuple

net/ipv6: Add support for path selection using hash of 5-tuple

Some operators prefer IPv6 path selection to use a standard 5-tuple
hash rather than just an L3 hash with the flow the label. To that end
add support to IPv6 for multipath hash policy similar to bf4e0a3db97eb
("net: ipv4: add support for ECMP hash policy choice"). The default
is still L3 which covers source and destination addresses along with
flow label and IPv6 protocol.

Signed-off-by: David Ahern <[email protected]>
Reviewed-by: Ido Schimmel <[email protected]>
Tested-by: Ido Schimmel <[email protected]>
Reviewed-by: Nikolay Aleksandrov <[email protected]>
Signed-off-by: David S. Miller <[email protected]>