s390/pci: remove redundant pci_bus_add_devices() on new bus

The pci_bus_add_devices() call in zpci_bus_create_pci_bus() is without
function since at this point no device could have been added to the
freshly created PCI bus.

Suggested-by: Bjorn Helgaas <helgaas@kernel.org>
Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>
Reviewed-by: Matthew Rosato <mjrosato@linux.ibm.com>
Link: https://lore.kernel.org/r/20230306151014.60913-4-schnelle@linux.ibm.com


Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>