PCI: rcar: Set root bus nr to that provided in DT

On ARM64, setting the root bus number to -1 causes probe failure.
Moreover, we should use the bus number specified in the DT as we could have
multiple PCIe controllers with different bus ranges.
Signed-off-by: Phil Edworthy <phil.edworthy@renesas.com>
Signed-off-by: Bjorn Helgaas <bhelgaas@google.com>
Acked-by: Simon Horman <horms+renesas@verge.net.au>

drivers/pci/host/pcie-rcar.c

@@ -362,7 +362,7 @@ static int rcar_pcie_setup(int nr, struct list_head *resource, struct rcar_pcie
 	struct resource *res;
 	int i;
 
-	pcie->root_bus_nr = -1;
+	pcie->root_bus_nr = pcie->busn.start;
 
 	/* Setup PCI resources */
 	for (i = 0; i < RCAR_PCI_MAX_RESOURCES; i++) {