usage of new PC `platform_drv` and `pci_decode`

[Duss Pirmin]

Hello Genodians

While debugging https://github.com/genodelabs/genode/issues/4538, I'm 
having trouble using the new `platfomr_drv` for the PC platform. From 
the release notes of 22.05, it seems that the new component `pci_decode` 
should be used to create the list of PCI devices.

Searching for this on master and staging I only find the component's 
source and its mention in the release notes - but not how it's used. I 
therefore extended my search. In the repository of skalk, I have found 
the branch `nvme_drv`, which adapts the NVMe driver for the new platform 
driver.

When I execute the run-script from this branch on different platforms 
(x86_64 qemu, an Intel 8th gen up-xtreme and my Intel 11700), 
`pci_decode` doesn't report any PCI devices.

Are there any further requirements to use the new platform driver on PC?

Best regards
Pirmin