arm64: dts: rockchip: Add PCIe v3 nodes to rock-3a

Add Nodes to Radxa ROCK3 Model A board to support PCIe v3.

Tested-by: Anand Moon <linux.amoon@gmail.com>
Signed-off-by: Chukun Pan <amadeus@jmu.edu.cn>
Link: https://lore.kernel.org/r/20221006152524.502445-3-amadeus@jmu.edu.cn


Signed-off-by: Heiko Stuebner <heiko@sntech.de>