symimgs

symimg on the boarddata is to show whether
1) the flash has enough space to store the same image as both main and bkup
2) to tell which image to upgrade during fw update

if symimgs = y, then fw update will always alternate between main and bkup.
essentially it is using it as image1 and image2, not main and backup
if symimgs = n, then fw update will always update main (image1) and does not update the bkup image