Add PCIe EP mode support for ls1028a.

Link: https://lore.kernel.org/r/20230209151050.233973-1-Frank.Li@nxp.comSigned-off-by: Xiaowei Bao <xiaowei.bao@nxp.com>
Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
Signed-off-by: Frank Li <Frank.Li@nxp>
Signed-off-by: Lorenzo Pieralisi <lpieralisi@kernel.org>
Reviewed-by: Alok Tiwari <alok.a.tiwari@oracle.com>
Acked-by: Roy Zang <Roy.Zang@nxp.com>