mediatek: dts: drop wrong sgmiisys0 node override

The sgmiisys0 override uses

  /delete-node/ mediatek,pnswap;

but mediatek,pnswap is a property, not a child node. The correct
directive would be /delete-property/. As a result, this statement never
had any effect and the property was never removed.

Drop the incorrect override.

Signed-off-by: Maxim Anisimov <maxim.anisimov.ua@gmail.com>
Link: https://github.com/openwrt/openwrt/pull/22046
Signed-off-by: Robert Marko <robimarko@gmail.com>

target/linux/mediatek/dts/mt7981b-keenetic-kap-630.dtsi

@@ -239,7 +239,3 @@
 	nvmem-cells = <&eeprom_factory_0>;
 	status = "okay";
 };
-
-&sgmiisys0 {
-	/delete-node/ mediatek,pnswap;
-};

target/linux/mediatek/dts/mt7981b-keenetic-kn-3911.dts

@@ -281,7 +281,3 @@
 	nvmem-cells = <&eeprom_factory_0>;
 	status = "okay";
 };
-
-&sgmiisys0 {
-	/delete-node/ mediatek,pnswap;
-};

target/linux/mediatek/dts/mt7981b-openwrt-one.dts

@@ -458,7 +458,3 @@
 	pinctrl-0 = <&pcie_pins>;
 	status = "okay";
 };
-
-&sgmiisys0 {
-	/delete-node/ mediatek,pnswap;
-};