ACPI: video: reset brightness on resume

Some machines seem to need the backlight brightness to be reset on resume.
Add support for doing so to the video module.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Matthew Garrett <mjg59@srcf.ucam.org>
Cc: Zhang Rui <rui.zhang@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Len Brown <len.brown@intel.com>