The backlight driver always writes a bogus value
from memory into the LCD brightness register.
Fix it up by adding bounds checks and
use a more sane default value.
While looking at the code, I noticed
that BACKLIGHT_CONTROL_SET probably ignores
the desired brightness level, too.
Note: Please test on real hardware, I don't own it.
cppcheck reported:
[rockbox/firmware/target/arm/s3c2440/mini2440/backlight-mini2440.c:53]: (error) Array 'log_brightness[13]' accessed at index 255, which is out of bounds.
Change-Id: Iaafa929a8adaa97b93ebcb66e1f6bd3bf0dad84e
