ARM: dts: AM33XX: fix ethernet and mdio default state

Make sure ethernet and mdio nodes are disabled by default and enable
them explicitly only on boards that actually use them.

Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>

arch/arm/boot/dts/am335x-nano.dts

@@ -344,6 +344,11 @@
 
 &mac {
 	dual_emac = <1>;
+	status = "okay";
+};
+
+&davinci_mdio {
+	status = "okay";
 };
 
 &cpsw_emac0 {