toshiba_acpi: Support new keyboard backlight type

Newer Toshiba models now come with a new (and different) keyboard
backlight implementation with three modes of operation: TIMER,
ON and OFF, and the LED is now controlled internally by the firmware.

This patch adds support for that type of backlight, changing the
existing code to accomodate the new implementation.

The timeout value range is now 1-60 seconds, and the accepted
modes are now: 1 (FN-Z), 2 (AUTO or TIMER), 8 (ON) and 10 (OFF),
this adds two new entries kbd_type and available_kbd_modes,
the first shows the keyboard type and the latter shows the
supported modes depending on the keyboard type.

Signed-off-by: Azael Avalos <coproscefalo@gmail.com>
Signed-off-by: Darren Hart <dvhart@linux.intel.com>