t2080: dts: Added PCIe DT nodes

T2080 integrated 4 PCIe controllers, which is compatible with
the PCI Express™ Base Specification, Revision 3.0, and this
patch is to add DT node for each PCIe controller.

Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Prabhakar Kushwaha <prabhakar.kushwaha@nxp.com>