ARM: dts: add hifsys reset for MediaTek SoCs

This adds missing hifsys reset parts in header files.

Tested-by: Frank Wunderlich <frank-w@public-files.de>
diff --git a/arch/arm/dts/mt7623.dtsi b/arch/arm/dts/mt7623.dtsi
index 448d1d7..64079c6 100644
--- a/arch/arm/dts/mt7623.dtsi
+++ b/arch/arm/dts/mt7623.dtsi
@@ -248,6 +248,13 @@
 		status = "disabled";
 	};
 
+	hifsys: syscon@1a000000 {
+		compatible = "mediatek,mt7623-hifsys", "syscon";
+		reg = <0x1a000000 0x1000>;
+		#clock-cells = <1>;
+		#reset-cells = <1>;
+	};
+
 	ethsys: syscon@1b000000 {
 		compatible = "mediatek,mt7623-ethsys", "syscon";
 		reg = <0x1b000000 0x1000>;