As the ath79 port of this device uses a combined kernel + root
partition the uboot bootcmd variable needs to be changed. As using
cli/luci is more convenient than opening up the case and using a uart
connection, lets unlock the uboot-env partition for write access.
Signed-off-by: Christoph Krapp <achterin@googlemail.com>
(cherry picked from commit 982c1f6e42c5b3e0f23eedd825a317a2872aa37b)