This allows the platform driver to take over control of DMA remapping and keeps NOVA-driven interrupt remapping active. genodelabs/genode#5002
DMA remapping hardware units use MSI for fault events. However, MSI were bound to the presence of a PCI configuration space. genodelabs/genode#5002
This patch changes the top-level directory layout as a preparatory step for improving the tools for managing 3rd-party source codes. The rationale is described in the issue referenced below. Issue #1082
