The environment is the canonical storage location of the mac address, so
we're killing off the global data location and moving everything to
querying the env directly.
The cpus that get converted here:
at91rm9200
mpc512x
mpc5xxx
mpc8260
mpc8xx
ppc4xx
Signed-off-by: Mike Frysinger <vapier@gentoo.org> CC: Ben Warren <biggerbadderben@gmail.com> CC: John Rigby <jrigby@freescale.com> CC: Stefan Roese <sr@denx.de>