[mvebu]: build squashfs on ubi and SysupgradeNAND images

Signed-off-by: Imre Kaloz <kaloz@openwrt.org>



git-svn-id: svn://svn.openwrt.org/openwrt/trunk@41360 3c298f89-4303-0410-b956-a3cf2f4a3e73