PCI: rcar: Use pci_host_probe() to register host

PCI: rcar: Use pci_host_probe() to register host

The rcar 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/20200522234832.954484-13-robh@kernel.org
Signed-off-by: Rob Herring <robh@kernel.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Cc: Marek Vasut <marek.vasut+renesas@gmail.com>
Cc: Yoshihiro Shimoda <yoshihiro.shimoda.uh@renesas.com>
Cc: linux-renesas-soc@vger.kernel.org