drivers/pci : enable pcie_layerscape code for lx2160a rev2

lx2160a rev1 uses pcie_layerscape_gen4 driver and lx2160a rev2 uses
pcie_layerscape driver.
Enable pcie_layerscape code for CONFIG_PCIE_LAYERSCAPE_GEN4.
Based on SoC and revision pcie controller probe will be invoked.

Signed-off-by: Wasim Khan <wasim.khan@nxp.com>
Signed-off-by: Priyanka Jain <priyanka.jain@nxp.com>