toshiba_acpi: Add WWAN RFKill support

A previuos patch added WWAN support to the driver, allowing to query
and set the device status.

This patch adds RFKill support for the recently introduced WWAN device,
making use of the WWAN and *wireless_status functions to query the
killswitch and (de)activate the device accordingly to its status.

Signed-off-by: Fabian Koester <fabian.koester@bringnow.com>
Signed-off-by: Azael Avalos <coproscefalo@gmail.com>
Signed-off-by: Darren Hart <dvhart@linux.intel.com>