If the net driver has setup a valid ethernet address and an ethernet
address is not set in the environment already, then set the environment
variables from the net driver setting.

This enables pxe booting on boards which don't set ethaddr env variable.

Signed-off-by: Rob Herring <rob.herring@calxeda.com>

Add a new function to the eth_device struct for programming a network
controller's hardware address.

After all network devices have been initialized and the proper MAC address
for each has been determined, make a device driver call to program the
address into the device.  Only device instances with valid unicast addresses
will be programmed.

Signed-off-by: Ben Warren <biggerbadderben@gmail.com>
Acked-by: Detlev Zundel <dzu@denx.de>
Tested-by: Prafulla Wadaskar <prafulla@marvell.com>
Tested-by: Heiko Schocher <hs@denx.de>
Tested-by: Thomas Chou <thomas@wytron.com.tw>

As this seems unclear, document how the flow of setting up
the MAC address is correct.

Signed-off-by: Heiko Schocher <hs@denx.de>

Text changed slightly, adding input from Mike Frysinger.

Signed-off-by: Wolfgang Denk <wd@denx.de>

Signed-off-by: Mike Frysinger <vapier@gentoo.org>
CC: Ben Warren <biggerbadderben@gmail.com>