rework IPv6 address dump logic

rework IPv6 address dump logic

Make the code more logical by moving the IPv6 address dump logic into the
different protocol interface enable handlers so it's clear which protocols
require interface IPv6 address tracking.
At the same time restructure the IPv6 address dump logic so less IPv6 address
netlink dumps are created.

Signed-off-by: Hans Dedecker <dedeckeh@gmail.com>