pci: Abort early if bus does not exist

When listing the devices on a PCI bus, the current code will blindly try
to access all devices. Internally this causes pci_bus_to_hose() to be
repeatedly called and output an error message every time. Prevent this
by calling pci_bus_to_hose() once and abort early if no bus was found.

Signed-off-by: Thierry Reding <treding@nvidia.com>
Signed-off-by: Simon Glass <sjg@chromium.org>

common/cmd_pci.c

@@ -42,12 +42,16 @@ void pci_header_show_brief(pci_dev_t dev);
  */
 void pciinfo(int BusNum, int ShortPCIListing)
 {
+	struct pci_controller *hose = pci_bus_to_hose(BusNum);
 	int Device;
 	int Function;
 	unsigned char HeaderType;
 	unsigned short VendorID;
 	pci_dev_t dev;
 
+	if (!hose)
+		return;
+
 	printf("Scanning PCI devices on bus %d\n", BusNum);
 
 	if (ShortPCIListing) {