PCI: Add generic pci_bus_claim_resources()

All PCI resources (bridge windows and BARs) should be inserted in the
iomem_resource and ioport_resource trees so we know what space is occupied
and what is available for other devices.  There's nothing arch-specific
about this, but it is currently done by arch-specific code.

Add a generic pci_bus_claim_resources() interface so we can migrate away
from the arch-specific code.

[bhelgaas: changelog]
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
CC: Arnd Bergmann <arnd@arndb.de>
CC: Yinghai Lu <yinghai@kernel.org>