As a fourth step, remove any remaining usages of
dev_node_t from drivers:

- ipwireless can be simplified a bit, as we do not need
  to pass around the (write-only) dev_node_t around.

- avma1_cs can be simplified as well, if we only keep the
  minor number around as "priv" data, not a full-fledged
  struct.
Acked-by: Jiri Kosina <jkosina@suse.cz>
Acked-by: Karsten Keil  <isdn@linux-pingi.de>
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>