wireless: Create 'device' symlink in sysfs

Some network interfaces of the wireless drivers lack the 'device'
symlink in sysfs.
This patch lets the drivers create the links.

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>