ACPI / video: Move ACPI_VIDEO_NOTIFY_* defines to acpi/video.h

acpi_video.c passed the ACPI_VIDEO_NOTIFY_* defines as type code to
acpi_notifier_call_chain(). Move these defines to acpi/video.h so
that acpi_notifier listeners can check the type code using these
defines.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Reviewed-by: Peter Wu <peter@lekensteyn.nl>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>