arm64: dts: lx2160a: Add PCIe controller DT nodes

The LX2160A integrated 6 PCIe Gen4 controllers.

Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
Reviewed-by: Minghuan Lian <Minghuan.Lian@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>