linux pci: Add dummy PCI access for shared contracts

Other implementations may update the PCI_State in Resource_Size() and
Map(). To share the contract with those implementations, we have to
simulate such accesses.

Change-Id: If994db22d91eb3707e555871d854c3a25a13678b
Signed-off-by: Nico Huber <nico.h@gmx.de>
Reviewed-on: https://review.coreboot.org/21206
Reviewed-by: Adrian-Ken Rueegsegger <ken@codelabs.ch>
Reviewed-by: Arthur Heymans <arthur@aheymans.xyz>