Link the net_device structure of the wireless part to the
corresponding device structure.

Without this, the sysfs node for this net_device would not have
'device' link.
Signed-off-by: Masakazu Mokuno <mokuno@sm.sony.co.jp>
Acked-by: Dan Williams <dcbw@redhat.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>