arm64: dts: ls1028a: Add PCIe EP nodes

Add PCIe EP nodes for ls1028a to support EP mode.

Signed-off-by: Xiaowei Bao <xiaowei.bao@nxp.com>
Signed-off-by: Li Yang <leoyang.li@nxp.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>