PCI: iproc: Use pci_host_probe() to register host

PCI: iproc: Use pci_host_probe() to register host

The iproc host driver does the same host registration and bus scanning
calls as pci_host_probe, so let's use it instead.

The only difference is pci_assign_unassigned_bus_resources() was called
instead of pci_bus_size_bridges() and pci_bus_assign_resources(). This
should be the same.

Link: https://lore.kernel.org/r/20200522234832.954484-12-robh@kernel.org
Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: Scott Branden <scott.branden@broadcom.com>
Cc: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Ray Jui <rjui@broadcom.com>
Cc: Scott Branden <sbranden@broadcom.com>
Cc: bcm-kernel-feedback-list@broadcom.com