hw/pci/pci: Remove multifunction parameter from pci_new_multifunction()

hw/pci/pci: Remove multifunction parameter from pci_new_multifunction()

There is also pci_new() which creates non-multifunction PCI devices.
Accordingly the parameter is always set to true when a multi function PCI
device is to be created.

The reason for the parameter's existence seems to be that it is used in the
internal PCI code as well which is the only location where it gets set to
false. This one usage can be resolved by factoring out an internal helper
function.

Remove this redundant, error-prone parameter.

Signed-off-by: Bernhard Beschow <shentey@gmail.com>
Message-Id: <20230304114043.121024-6-shentey@gmail.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>