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: NAnisse Astier <anisse@astier.eu>
Reviewed-by: NBen Hutchings <ben@decadent.org.uk>
Acked-by: Nmaximilian attems <max@stro.at>
Signed-off-by: NMichal Marek <mmarek@suse.cz>