staging: wilc1000: remove registering of ndo_do_ioctl callback

Remove registering of ndo_do_ioctl in wilc_netdev_ops structure.
As RSSI information is already avaliable through cfg80211, so remove
the IOCTL call use to fetch the same information. Wext support is not
present in the driver. Its also done to address the TODO list item
mentioned below:

"use wext-core handling instead of private SIOCSIWPRIV implementation"

Signed-off-by: Ajay Singh <ajay.kathat@microchip.com>
Reviewed-by: Claudiu Beznea <claudiu.beznea@microchip.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>