net: phy: dp83867: allow RGMII_TXID/RGMII_RXID interface types

Currently dp83867 driver returns error if phy interface type
PHY_INTERFACE_MODE_RGMII_RXID is used to set the rx only internal
delay. Similarly issue happens for PHY_INTERFACE_MODE_RGMII_TXID.
Fix this by checking also the interface type if a particular delay
value is missing in the phy dt bindings. Also update the DT document
accordingly.

Signed-off-by: Murali Karicheri <m-karicheri2@ti.com>
Signed-off-by: Sekhar Nori <nsekhar@ti.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/drivers/net/phy/dp83867.c b/drivers/net/phy/dp83867.c
index e84ae08..ca1b462 100644
--- a/drivers/net/phy/dp83867.c
+++ b/drivers/net/phy/dp83867.c
@@ -132,12 +132,16 @@ static int dp83867_of_init(struct phy_device *phydev)
 
 	ret = of_property_read_u32(of_node, "ti,rx-internal-delay",
 				   &dp83867->rx_id_delay);
-	if (ret)
+	if (ret &&
+	    (phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
+	     phydev->interface == PHY_INTERFACE_MODE_RGMII_RXID))
 		return ret;
 
 	ret = of_property_read_u32(of_node, "ti,tx-internal-delay",
 				   &dp83867->tx_id_delay);
-	if (ret)
+	if (ret &&
+	    (phydev->interface == PHY_INTERFACE_MODE_RGMII_ID ||
+	     phydev->interface == PHY_INTERFACE_MODE_RGMII_TXID))
 		return ret;
 
 	return of_property_read_u32(of_node, "ti,fifo-depth",