pci: pcie_layerscape_fixup_common: include fdt_support.h for ft_pci_setup

The function prototype for ft_pci_setup is inside fdt_support.h, we need
to include that header.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>