[mvebu]: handle sysupgrade tar files on the WRT1900AC

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



git-svn-id: svn://svn.openwrt.org/openwrt/trunk@41647 3c298f89-4303-0410-b956-a3cf2f4a3e73
[mvebu]: mark the default WRT1900AC image "factory"

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


git-svn-id: svn://svn.openwrt.org/openwrt/trunk@41648 3c298f89-4303-0410-b956-a3cf2f4a3e73