PCI: layerscape: Add support for LS1043a and LS2080a

Both LS1043a and LS2080a are based on ARMv8 64-bit architecture and have
similar PCIe implementation.  LUT is added to controller.

Add LS1043a and LS2080a support.

[bhelgaas: move unused field removal into separate patch, include DT update]
Signed-off-by: Bhupesh Sharma <bhupesh.sharma@freescale.com> (DT update)
Signed-off-by: Minghuan Lian <Minghuan.Lian@freescale.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Arnd Bergmann <arnd@arndb.de> (DT update)