PCI: armada: Reorder struct armada8k_pcie

Reorder the device-specific struct to put the DesignWare generic struct
pcie_port first.  No functional change intended.

Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Reviewed-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>