libpci: Implement virtual config space for provides without access to config space

libpci: Implement virtual config space for provides without access to config space

Add a new pci_dev member no_config_access which signals that there is no
access to config space for particular device. Reading operation in this
case should return data from emulated virtual config space. For provides
there is a new helper function pci_generic_read() which emulates config
spaces based on struct pci_dev members.