net/macb: add DT support for Cadence macb/gem driver

Allow the device tree to provide the mac address and the phy mode.

Signed-off-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
[nicolas.ferre@atmel.com: change "compatible" node property, doc and DT hwaddr]
Signed-off-by: Nicolas Ferre <nicolas.ferre@atmel.com>
[jamie@jamieiles.com: add "gem" compatibility strings and doc]
Acked-by: Jamie Iles<jamie@jamieiles.com>
Acked-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/ethernet/cadence/macb.h b/drivers/net/ethernet/cadence/macb.h
index 1931078..335e288 100644
--- a/drivers/net/ethernet/cadence/macb.h
+++ b/drivers/net/ethernet/cadence/macb.h
@@ -532,6 +532,8 @@
 	unsigned int 		link;
 	unsigned int 		speed;
 	unsigned int 		duplex;
+
+	phy_interface_t		phy_interface;
 };
 
 static inline bool macb_is_gem(struct macb *bp)