ACPI: video: Stop trying to use vendor backlight control on laptops from after ~2012

ACPI: video: Stop trying to use vendor backlight control on laptops from after ~2012

There have been 2 separate reports now about a non working
"dell_backlight" device getting registered under /sys/class/backlight
1 report for a Raptor Lake based Dell and 1 report for a Meteor Lake
(development) platform.

On hw from the last 10 years dell-laptop will not register "dell_backlight"
because acpi_video_get_backlight_type() will return acpi_backlight_video
there if called before the GPU/kms driver loads. So it does not matter if
the GPU driver's native backlight is registered after dell-laptop loads.

But it seems that on the latest generation laptops the ACPI tables
no longer contain acpi_video backlight control support which causes
acpi_video_get_backlight_type() to return acpi_backlight_vendor causing
"dell_backlight" to get registered if the dell-laptop module is loaded
before the GPU/kms driver.

Vendor specific backlight control like the "dell_backlight" device is
only necessary on quite old hw (from before acpi_video backlight control
was introduced). Work around "dell_backlight" registering on very new
hw (where acpi_video backlight control seems to be no more) by making
acpi_video_get_backlight_type() return acpi_backlight_none instead
of acpi_backlight_vendor as final fallback when the ACPI tables have
support for Windows 8 or later (laptops from after ~2012).

Suggested-by: Matthew Garrett <mjg59@srcf.ucam.org>
Reported-by: AceLan Kao <acelan.kao@canonical.com>
Closes: https://lore.kernel.org/platform-driver-x86/20230607034331.576623-1-acelan.kao@canonical.com/
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>