ARM: dts: BCM53573: Add cells sizes to PCIe node

This fixes:
arch/arm/boot/dts/broadcom/bcm47189-luxul-xap-1440.dtb: pcie@2000: '#address-cells' is a required property
        From schema: /lib/python3.10/site-packages/dtschema/schemas/pci/pci-bus.yaml
arch/arm/boot/dts/broadcom/bcm47189-luxul-xap-1440.dtb: pcie@2000: '#size-cells' is a required property
        From schema: /lib/python3.10/site-packages/dtschema/schemas/pci/pci-bus.yaml

Two properties that need to be added later are "device_type" and
"ranges". Adding "device_type" on its own causes a new warning and the
value of "ranges" needs to be determined yet.
Signed-off-by: Rafał Miłecki <rafal@milecki.pl>
Link: https://lore.kernel.org/r/20230707114004.2740-3-zajec5@gmail.comSigned-off-by: Florian Fainelli <florian.fainelli@broadcom.com>

arch/arm/boot/dts/broadcom/bcm53573.dtsi

@@ -127,6 +127,9 @@ uart0: serial@300 {
 
 		pcie0: pcie@2000 {
 			reg = <0x00002000 0x1000>;
+
+			#address-cells = <3>;
+			#size-cells = <2>;
 		};
 
 		usb2: usb2@4000 {