staging/wilc1000: use device pointer for phy creation

wilc_create_wiphy tries to get a pointer to a device from the
global wilc_sdio_func variable. This is a layering violation
and we can use the wilc_dev->dev pointer instead.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>