staging: wilc1000: remove use of driver_handler_id & ifc_id

Removed the 'driver_handler_id' & 'ifc_id' elements and used 'idx' to
identify the handler.

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