staging: mt7621-dts: add missing device_type in pcie root ports

According to the YAML schema 'pci-bus.yaml' the 'device_type'
property is mandatory for all pcie root ports. Hence add it.

Signed-off-by: Sergio Paracuellos <sergio.paracuellos@gmail.com>
Link: https://lore.kernel.org/r/20210506170742.28196-3-sergio.paracuellos@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/mt7621-dts/mt7621.dtsi

@@ -515,6 +515,7 @@
 			reg = <0x0000 0 0 0 0>;
 			#address-cells = <3>;
 			#size-cells = <2>;
+			device_type = "pci";
 			#interrupt-cells = <1>;
 			interrupt-map-mask = <0 0 0 0>;
 			interrupt-map = <0 0 0 0 &gic GIC_SHARED 4 IRQ_TYPE_LEVEL_HIGH>;
@@ -525,6 +526,7 @@
 			reg = <0x0800 0 0 0 0>;
 			#address-cells = <3>;
 			#size-cells = <2>;
+			device_type = "pci";
 			#interrupt-cells = <1>;
 			interrupt-map-mask = <0 0 0 0>;
 			interrupt-map = <0 0 0 0 &gic GIC_SHARED 24 IRQ_TYPE_LEVEL_HIGH>;
@@ -535,6 +537,7 @@
 			reg = <0x1000 0 0 0 0>;
 			#address-cells = <3>;
 			#size-cells = <2>;
+			device_type = "pci";
 			#interrupt-cells = <1>;
 			interrupt-map-mask = <0 0 0 0>;
 			interrupt-map = <0 0 0 0 &gic GIC_SHARED 25 IRQ_TYPE_LEVEL_HIGH>;