Some scanners provide hardware assistance in frame assemling, i.e.
horizontal and vertical offset to previous frame is provided. This
commit improves code to utilise that assistance. Sensors without
hardware assistance will use software algorithm, which was also
improved to do search in horizontal direction.
AES3500 and AES4000 are pretty similar devices, have same
command send, the only difference is in image size and init sequence.
Extract common routines from AES4K to be used later in AES3500 driver
https://bugs.freedesktop.org/show_bug.cgi?id=64351