PCI: Extend enable to check for any optional resource

pci_enable_resources() checks if device's io and mem resources are all
assigned and disallows enable if any resource failed to assign (*) but
makes an exception for the case of disabled extension ROM. There are other
optional resources, however.

Add pci_resource_is_optional() and use it instead of
pci_resource_is_disabled_rom() to cover also IOV resources that are also
optional as per pbus_size_mem().

As there will be more users of pci_resource_is_optional() inside
setup-bus.c in changes coming up after this one, the function is placed
there.

(*) In practice, resource fitting code calls reset_resource() for any
resource it fails to assign which clears resource's ->flags causing
pci_enable_resources() to never detect failed resource assignments.
This seems undesirable internal logic inconsistency, effectively
reset_resource() prevents pci_enable_resources() from functioning as
intended. This is one step of many that will be needed towards removing
reset_resource().

Link: https://lore.kernel.org/r/20241216175632.4175-20-ilpo.jarvinen@linux.intel.com


Signed-off-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Tested-by: Xiaochun Lee <lixc17@lenovo.com>