mediatek: remove DTS property added by mistake

Remove bogus 'phy-handle = <&phy0>;', an undefined reference.

Fixes: c8c2f52262 ("mediatek: add support for Zbtlink ZBT-Z8102AX")
Signed-off-by: Daniel Golle <[email protected]>

target/linux/mediatek/dts/mt7981b-zbtlink-zbt-z8102ax.dts

@@ -140,7 +140,6 @@
 		compatible = "mediatek,eth-mac";
 		reg = <0>;
 		phy-mode = "2500base-x";
-		phy-handle = <&phy0>;
 
 		nvmem-cell-names = "mac-address";
 		nvmem-cells = <&macaddr_factory_4 2>;