ACPI: video: Add auto_detect arg to __acpi_video_get_backlight_type()

Allow callers of __acpi_video_get_backlight_type() to pass a pointer
to a bool which will get set to false if the backlight-type comes from
the cmdline or a DMI quirk and set to true if auto-detection was used.

And make __acpi_video_get_backlight_type() non static so that it can
be called directly outside of video_detect.c .

While at it turn the acpi_video_get_backlight_type() and
acpi_video_backlight_use_native() wrappers into static inline functions
in include/acpi/video.h, so that we need to export one less symbol.

Fixes: 5aa9d943 ("ACPI: video: Don't enable fallback path for creating ACPI backlight by default")
Cc: All applicable <stable@vger.kernel.org>
Reviewed-by: Mario Limonciello <mario.limonciello@amd.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>