toshiba_acpi: Add keyboard backlight mode change event

A previous patch added support to handle more events.

This patch adds support to update the sysfs group whenever we receive
a 0x92 event, which indicates a change in the keyboard backlight mode,
removing the update group code from toshiba_kbd_bl_mode_store, as it is
no longer needed there.

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