This driver is written in a way that is should also work without
DT, but it had a compile time dependency on CONFIG_OFTREE.
Fixes:
drivers/built-in.o: In function `dwc_probe_dt':
drivers/net/designware.c:413: undefined reference to `of_get_phy_mode'
Signed-off-by: Lucas Stach <dev@lynxeye.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>