octeon: sysupgrade: fix test for rootfs device

Signed-off-by: Stijn Tintel <stijn@linux-ipv6.be>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@43522 3c298f89-4303-0410-b956-a3cf2f4a3e73
octeon: sysupgrade: rename old kernel after mounting /boot

Signed-off-by: Stijn Tintel <stijn@linux-ipv6.be>

git-svn-id: svn://svn.openwrt.org/openwrt/trunk@43523 3c298f89-4303-0410-b956-a3cf2f4a3e73