toshiba_acpi: Add support for Panel Power ON

Toshiba laptops come with a feature called "Panel Open - Power ON",
which makes the laptop turn on whenever the LID is opened.

This patch adds support for such feature, by creating a sysfs entry
named "panel_power_on", accepting only two values, 0 to disable and
1 to enable such feature, however, a reboot is needed on every mode
change.

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