deb-pkg: add a hook argument to match debian hooks parameters

We now provide the installed image path to the kernel hooks.

This should allow the package to better integrate with debian hooks, and
should not be too disruptive of hooks supporting only one parameter.

Signed-off-by: Anisse Astier <anisse@astier.eu>
Reviewed-by: Ben Hutchings <ben@decadent.org.uk>
Acked-by: maximilian attems <max@stro.at>
Signed-off-by: Michal Marek <mmarek@suse.cz>