This fixes the issues with the jffs2 images on various boards. Using
JFFS2 on devices with 4KiB erase sectors is not safe:
http://lists.infradead.org/pipermail/linux-mtd/2011-June/036591.html
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@29521 3c298f89-4303-0410-b956-a3cf2f4a3e73