S5PC11X: JPEG: add ioctl to export memory configuration

This allows userspace libs3cjpeg to read memory configuration
from the kernel instead of using the hardcoded value.

Change-Id: I61248d659dbccf2e6cc656adc7fdf18773c2fcbd
crespo: optimize JPEG memory configuration

Only 1MB is required for encoding of VGA JPEG images (used by FFC).
Note that thumbnail encoding function is not used.

Requires userspace change (http://review.cyanogenmod.org/56795).