uboot-phytec

net: Handle ethaddr changes as an env callback

When the ethaddr is changed in the env, update the device pdata at the
same time (only if it is probed for the DM case; only if registered for
the non-DM case). Again this gets us closer to completely non-polled
env needed to simplify the net_loop.

This requires that the NET feature select the REGEX feature.

Signed-off-by: Joe Hershberger <joe.hershberger@ni.com>