armv8: fsl-layerscape: fix config dependency for layerscape pci code

Fixes a link error on layerscape platform, linking fails with CONFIG_PCI
set and CONFIG_PCI_LAYERSCAPE unset.

Signed-off-by: Alex Marginean <alexm.osslist@gmail.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
Reviewed-by: Prabhakar Kushwaha <prabhakar.kushwaha@nxp.com>