This introduces support for the Aspeed JPEG format, where the new frame
can refer to previous frame to reduce the amount of compressed data.
The concept is similar to I/P frame of video compression. It will
compare the new frame with previous one to decide which macroblock's
data is changed, and only the changed macroblocks will be compressed.

This Aspeed JPEG format is used by the video engine on Aspeed platforms,
which is generally adapted for remote KVM.
Signed-off-by: Jammy Huang <jammy_huang@aspeedtech.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>