toshiba_acpi: Add support for bluetooth toggling through rfkill (v8)

There's been a patch floating around for toshiba_acpi that exports an ad-hoc
/proc interface to toggle the bluetooth adapter in a large number of Toshiba
laptops. I'm not sure if it's still relevant for the latest models, but it is
still required for older models such as my Tecra M3.

This change pulls in the low level Toshiba-specific code from the old patch and
sets up an rfkill device and a polled input device to track the state of the
hardware kill-switch.

Signed-off-by: Philip Langdale <philipl@overt.org>
Acked-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Signed-off-by: John W. Linville <linville@tuxdriver.com>