Move this to Kconfig and clean up board config files that use it. Also
rename it to CONFIG_ETH_DESIGNWARE to fit with the naming that exists
in drivers/net/Kconfig.
Signed-off-by: NSimon Glass <sjg@chromium.org>
Version 1:
Acked-by: NJoe Hershberger <joe.hershberger@ni.com>