net: mdiobus: Debug print fwnode handle instead of raw pointer

Was slightly misleading before, because printed is pointer to fwnode,
not to phy device, as placement in message suggested.  Include header
for dev_dbg() declaration while at it.

Output before:

    [  +0.001247] mdio_bus f802c000.ethernet-ffffffff: registered phy 2612f00a fwnode at address 3

Output after:

    [  +0.001229] mdio_bus f802c000.ethernet-ffffffff: registered phy fwnode /ahb/apb/ethernet@f802c000/ethernet-phy@3 at address 3
Reviewed-by: Florian Fainelli <florian.fainelli@broadcom.com>
Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: Alexander Dahl <ada@thorsis.com>
Link: https://patch.msgid.link/20240906062256.11289-1-ada@thorsis.comSigned-off-by: Paolo Abeni <pabeni@redhat.com>

drivers/net/mdio/fwnode_mdio.c

@@ -7,6 +7,7 @@
  */
 
 #include <linux/acpi.h>
+#include <linux/dev_printk.h>
 #include <linux/fwnode_mdio.h>
 #include <linux/of.h>
 #include <linux/phy.h>
@@ -104,7 +105,7 @@ int fwnode_mdiobus_phy_device_register(struct mii_bus *mdio,
 		return rc;
 	}
 
-	dev_dbg(&mdio->dev, "registered phy %p fwnode at address %i\n",
+	dev_dbg(&mdio->dev, "registered phy fwnode %pfw at address %i\n",
 		child, addr);
 	return 0;
 }