netns: constify net_hash_mix() and various callers

const qualifiers ease code review by making clear
which objects are not written in a function.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --cc include/linux/udp.h
Simple merge

diff --cc include/net/inet_hashtables.h
Simple merge

diff --cc include/net/netns/hash.h
Simple merge

diff --cc net/ipv4/devinet.c
Simple merge

diff --cc net/ipv4/inet_hashtables.c
Simple merge

diff --cc net/ipv4/ping.c
Simple merge

diff --cc net/ipv4/udp.c
Simple merge

diff --cc net/ipv6/inet6_hashtables.c
Simple merge

diff --cc net/ipv6/udp.c
Simple merge