Fix RGMII-ID handling in gianfar

The TSEC/eTSEC can detect the interface to the PHY automatically,
but it isn't able to detect whether the RGMII connection needs internal
delay.  So we need to detect that change in the device tree, propagate
it to the platform data, and then check it if we're in RGMII.  This fixes
a bug on the 8641D HPCN board where the Vitesse PHY doesn't use the delay
for RGMII.

Signed-off-by: Andy Fleming <afleming@freescale.com>
diff --git a/drivers/net/gianfar.c b/drivers/net/gianfar.c
index d7a1a58..f926905 100644
--- a/drivers/net/gianfar.c
+++ b/drivers/net/gianfar.c
@@ -420,8 +420,18 @@
 	if (ecntrl & ECNTRL_REDUCED_MODE) {
 		if (ecntrl & ECNTRL_REDUCED_MII_MODE)
 			return PHY_INTERFACE_MODE_RMII;
-		else
+		else {
+			phy_interface_t interface = priv->einfo->interface;
+
+			/*
+			 * This isn't autodetected right now, so it must
+			 * be set by the device tree or platform code.
+			 */
+			if (interface == PHY_INTERFACE_MODE_RGMII_ID)
+				return PHY_INTERFACE_MODE_RGMII_ID;
+
 			return PHY_INTERFACE_MODE_RGMII;
+		}
 	}
 
 	if (priv->einfo->device_flags & FSL_GIANFAR_DEV_HAS_GIGABIT)