Revert "ACPI / video: change acpi-video brightness_switch_enabled default to 0"

This reverts commit 886129a8eebeb (ACPI / video: change acpi-video
brightness_switch_enabled default to 0) as it is reported to cause
problems to happen.

Fixes: 886129a8eebeb (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>
diff --git a/drivers/acpi/video.c b/drivers/acpi/video.c
index 071c1df..29649c1 100644
--- a/drivers/acpi/video.c
+++ b/drivers/acpi/video.c
@@ -68,7 +68,7 @@
 MODULE_DESCRIPTION("ACPI Video Driver");
 MODULE_LICENSE("GPL");
 
-static bool brightness_switch_enabled;
+static bool brightness_switch_enabled = 1;
 module_param(brightness_switch_enabled, bool, 0644);
 
 /*