net: phy: Don't create phy device when there is no phy

In get_phy_device_by_mask(), when no phy is found, we should not
create any phy device.

Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>

drivers/net/phy/phy.c

@@ -672,7 +672,8 @@ static struct phy_device *get_phy_device_by_mask(struct mii_dev *bus,
 			return phydev;
 	}
 	printf("Phy %d not found\n", ffs(phy_mask) - 1);
-	return phy_device_create(bus, ffs(phy_mask) - 1, 0xffffffff, interface);
+
+	return NULL;
 }
 
 /**