PCI: keystone: 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: NShawn Guo <shawn.guo@linaro.org>
Signed-off-by: NLorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Murali Karicheri <m-karicheri2@ti.com>

drivers/pci/controller/dwc/pci-keystone.c

@@ -347,7 +347,6 @@ static int __init ks_add_pcie_port(struct keystone_pcie *ks_pcie,
 		}
 	}
 
-	pp->root_bus_nr = -1;
 	pp->ops = &keystone_pcie_host_ops;
 	ret = ks_dw_pcie_host_init(ks_pcie, ks_pcie->msi_intc_np);
 	if (ret) {