This reverts commit 886129a8 (ACPI / video: change acpi-video
brightness_switch_enabled default to 0) as it is reported to cause
problems to happen.

Fixes: 886129a8 (ACPI / video: change acpi-video brightness_switch_enabled default to 0)
Link: http://marc.info/?l=linux-acpi&m=140534286826819&w=2
Reported by: Bjørn Mork <bjorn@mork.no>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>