pcmcia: dev_node removal (drivers with unregister_netdev check)

As a third step, remove any usage of dev_node_t from drivers which
only wrote to this typedef/struct, except to determine whether
register_netdev() succeeded previously. However, the function calling
unregister_netdev() was only ever called by the PCMCIA core if
register_netdev() succeeded previously. The lonely exception was
easily fixed.

CC: netdev@vger.kernel.org
CC: linux-wireless@vger.kernel.org
Signed-off-by: Dominik Brodowski <linux@dominikbrodowski.net>