arm64: dts: rockchip: add missing #interrupt-cells to rk356x pcie2x1

This fixes the following issue:
  pcieport 0000:00:00.0: of_irq_parse_pci: failed with rc=-22
Signed-off-by: Jensen Huang <jensenhuang@friendlyarm.com>
Link: https://lore.kernel.org/r/20230113064457.7105-1-jensenhuang@friendlyarm.comSigned-off-by: Heiko Stuebner <heiko@sntech.de>

arch/arm64/boot/dts/rockchip/rk356x.dtsi

@@ -966,6 +966,7 @@ pcie2x1: pcie@fe260000 {
 		clock-names = "aclk_mst", "aclk_slv",
 			      "aclk_dbi", "pclk", "aux";
 		device_type = "pci";
+		#interrupt-cells = <1>;
 		interrupt-map-mask = <0 0 0 7>;
 		interrupt-map = <0 0 0 1 &pcie_intc 0>,
 				<0 0 0 2 &pcie_intc 1>,