toshiba_acpi: Adapt kbd_bl_timeout_store to the new kbd type

With the introduction of the new keyboard backlight
implementation, the *_timeout_store function is
broken, as it only supports the first kbd_type.

This patch adapts such function for the new kbd_type,
as well as converts from using sscanf to kstrtoint.

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