platform/x86: samsung-laptop: Add support for Samsung's NP7[34]0U3E models.

These models have only 4 levels of keyboard backlight brightness and forget
how to work the backlight after resuming from S3 sleep. I've added a quirk
to set the appropriate number of backlight levels, and one to re-enable the
keyboard backlight on resume.

(Whitespace cleaned up by Matthew Garrett)

Signed-off-by: Scott Thrasher <scott.thrasher@gmail.com>
Signed-off-by: Matthew Garrett <matthew.garrett@nebula.com>