LS1012FRDM is supported but there's no flashing instruction in README.
This patch adds it.
While at it, add a missing saveenv for MAC address setup.
Signed-off-by: Pawel Dembicki <paweldembicki@gmail.com>
[add comment about saveenv]
Signed-off-by: Adrian Schmutzler <freifunk@adrianschmutzler.de>