dt-bindings: pci: layerscape-pci: Add compatible strings for ls1088a and ls2088a

Add compatible strings for ls1088a and ls2088a.

Link: https://lore.kernel.org/r/20200918080024.13639-6-Zhiqiang.Hou@nxp.com


Signed-off-by: Xiaowei Bao <xiaowei.bao@nxp.com>
Signed-off-by: Hou Zhiqiang <Zhiqiang.Hou@nxp.com>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: Rob Herring <robh@kernel.org>