PCI: brcmstb: Use pci_host_probe() to register host

PCI: brcmstb: Use pci_host_probe() to register host

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

Link: https://lore.kernel.org/r/20200522234832.954484-5-robh@kernel.org
Tested-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Cc: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
Cc: bcm-kernel-feedback-list@broadcom.com
Cc: linux-rpi-kernel@lists.infradead.org