ACPI: video: Allow GPU drivers to report no panels

ACPI: video: Allow GPU drivers to report no panels

[ Upstream commit 00a734104af7d878f1252d49eff9298785c6cbdc ]

The current logic for the ACPI backlight detection will create
a backlight device if no native or vendor drivers have created
8 seconds after the system has booted if the ACPI tables
included backlight control methods.

If the GPU drivers have loaded, they may be able to report whether
any LCD panels were found.  Allow using this information to factor
in whether to enable the fallback logic for making an acpi_video0
backlight device.

Suggested-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Mario Limonciello <mario.limonciello@amd.com>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>