Since v3.7 the acpi backlight driver doesn't work correctly in several
machines because ACPI code has different code for Windows 8, and the
rest.

The commit ea45ea70 (in v3.11-rc2) tried to fix this problem by using the
intel backlight driver, however it introduced several other issues in
different machines.

This patch fixes both regressions by blacklisting the win8 OSI, so we
are back to v3.6 behavior, and it should remain that way until the intel
backlight driver is fixed.

Since v3.7, users have been forced to fix the initial regression by
modifying the boot arguments (acpi_osi="!Windows 2012").

Once the Intel backlight driver works correctly for all machines, this
blacklist can be removed and that driver can be used instead.

References: https://bugzilla.kernel.org/show_bug.cgi?id=60682Reported-by: Danny Baumann <dannybaumann@web.de>
Reported-by: Philipp Richter <richterphilipp.pops@gmail.com>
Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>