platform/x86: panasonic-laptop: Use acpi_video_get_backlight_type()

Use acpi_video_get_backlight_type() to determine if we should register
the panasonic specific backlight interface. To avoid registering this
on systems where the ACPI or GPU native backlight control methods
should be used instead.

Tested-by: Stefan Seyfried <seife+kernel@b1-systems.com>
Tested-by: Kenneth Chan <kenneth.t.chan@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Link: https://lore.kernel.org/r/20220624112340.10130-8-hdegoede@redhat.com