acer-wmi: Add acpi_backlight=video quirk for the Acer KAV80

acer-wmi: Add acpi_backlight=video quirk for the Acer KAV80

commit 183fd8fcd7f8afb7ac5ec68f83194872f9fecc84 upstream.

The acpi-video backlight interface on the Acer KAV80 is broken, and worse
it causes the entire machine to slow down significantly after a suspend/resume.

Blacklist it, and use the acer-wmi backlight interface instead. Note that
the KAV80 is somewhat unique in that it is the only Acer model where we
fall back to acer-wmi after blacklisting, rather then using the native
(e.g. intel) backlight driver. This is done because there is no native
backlight interface on this model.

BugLink: https://bugzilla.redhat.com/show_bug.cgi?id=1128309
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Darren Hart <dvhart@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>