PCI: armada8k: Drop unnecessary root_bus_nr setting

Function dw_pcie_host_init() already initializes the root_bus_nr field
of 'struct pcie_port', so the -1 assignment prior to calling
dw_pcie_host_init() in platform specific driver is not really needed.
Drop it.
Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Acked-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

drivers/pci/controller/dwc/pcie-armada8k.c

@@ -172,7 +172,6 @@ static int armada8k_add_pcie_port(struct armada8k_pcie *pcie,
 	struct device *dev = &pdev->dev;
 	int ret;
 
-	pp->root_bus_nr = -1;
 	pp->ops = &armada8k_pcie_host_ops;
 
 	pp->irq = platform_get_irq(pdev, 0);