net: phy: xgmiitorgmii: Support generic PHY status read

Some PHY drivers like the generic one do not provide a read_status
callback on their own but rely on genphy_read_status being called
directly.

With the current code, this results in a NULL function pointer call.
Call genphy_read_status instead when there is no specific callback.
Signed-off-by: Paul Kocialkowski <paul.kocialkowski@bootlin.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/phy/xilinx_gmii2rgmii.c

@@ -44,7 +44,10 @@ static int xgmiitorgmii_read_status(struct phy_device *phydev)
 	u16 val = 0;
 	int err;
 
+	if (priv->phy_drv->read_status)
 		err = priv->phy_drv->read_status(phydev);
+	else
+		err = genphy_read_status(phydev);
 	if (err < 0)
 		return err;