Revert "ACPI / video: Always call acpi_video_init_brightness() on init"

Revert commit c04c697c

 (ACPI / video: Always call acpi_video_init_brightness()
on init), because it breaks eDP backlight at 1920x1080 on Acer Aspire S3
for Trevor Bortins.

References: https://bugs.freedesktop.org/show_bug.cgi?id=68355
Reported-and-bisected-by: Trevor Bortins <enabfluw@gmail.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>