coccinelle: also catch kzfree() issues

Since commit 3ef0e5ba ('slab: introduce kzfree()'),
kfree() is no more the only function to be considered:
kzfree() should be recognized too.

In particular, kzfree() must not be called on memory
allocated through devm_*() functions.

Cc: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Yann Droneaud <ydroneaud@opteya.com>
Signed-off-by: Michal Marek <mmarek@suse.com>