arm: dts: mediatek: add PCIe node for MT7622

This patch adds PCIe node in dts for Mediatek MT7622 Soc.

diff --git a/arch/arm/dts/mt7622-rfb.dts b/arch/arm/dts/mt7622-rfb.dts
index f05c3fe..317fc78 100644
--- a/arch/arm/dts/mt7622-rfb.dts
+++ b/arch/arm/dts/mt7622-rfb.dts
@@ -46,8 +46,39 @@
 	};
 };
 
+&pcie {
+	pinctrl-names = "default";
+	pinctrl-0 = <&pcie0_pins>, <&pcie1_pins>;
+	status = "okay";
+
+	pcie@0,0 {
+		status = "okay";
+	};
+
+	pcie@1,0 {
+		status = "okay";
+	};
+};
 
 &pinctrl {
+	pcie0_pins: pcie0-pins {
+		mux {
+			function = "pcie";
+			groups = "pcie0_pad_perst",
+				 "pcie0_1_waken",
+				 "pcie0_1_clkreq";
+		};
+	};
+
+	pcie1_pins: pcie1-pins {
+		mux {
+			function = "pcie";
+			groups = "pcie1_pad_perst",
+				 "pcie1_0_waken",
+				 "pcie1_0_clkreq";
+		};
+	};
+
 	snfi_pins: snfi-pins {
 		mux {
 			function = "flash";