platform/x86: asus-wmi: Move acpi_backlight=vendor quirks to ACPI video_detect.c

Remove the asus-wmi quirk_entry.wmi_backlight_power quirk-flag, which
called acpi_video_set_dmi_backlight_type(acpi_backlight_vendor) and replace
it with acpi/video_detect.c video_detect_dmi_table[] entries using the
video_detect_force_vendor callback.

acpi_video_set_dmi_backlight_type() is troublesome because it may end up
getting called after other backlight drivers have already called
acpi_video_get_backlight_type() resulting in the other drivers
already being registered even though they should not.

Note no entries are dropped from the dmi_system_id table in asus-nb-wmi.c.
This is because the entries using the removed wmi_backlight_power flag
also use other model specific quirks from the asus-wmi quirk_entry struct.
So the quirk_asus_x55u struct and the entries pointing to it cannot be
dropped.

Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>