[IPV4] inet_peer: Group together avl_left, avl_right, v4daddr to speedup lookups on some CPUS

Lot of routers/embedded devices still use CPUS with 16/32 bytes cache
lines.  (486, Pentium, ...  PIII) It makes sense to group together
fields used at lookup time so they fit in one cache line.  This reduce
cache footprint and speedup lookups.

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: David S. Miller <davem@davemloft.net>