usb: dm: Make "usb info" use usb_for_each_root_dev()

The old dm "usb info" implementation has several issues:

1) NULL pointer deref when a bus has no children
2) Not showing usb devices on busses without an emulated root-hub (otg host)
3) Attempting to show devices on inactive busses
4) "usb info" Would cause some hosts to get re-probed something which only
   "usb reset" should do

TL;DR: proper iterating over usb bus root devs is hard, use the helper
for it.

Reported-by: Bernhard Nortmann <bernhard.nortmann@web.de>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

cmd/usb.c

@@ -593,39 +593,20 @@ static void do_usb_start(void)
 }
 
 #ifdef CONFIG_DM_USB
-static void show_info(struct udevice *dev)
+static void usb_show_info(struct usb_device *udev)
 {
 	struct udevice *child;
-	struct usb_device *udev;
 
-	udev = dev_get_parent_priv(dev);
 	usb_display_desc(udev);
 	usb_display_config(udev);
-	for (device_find_first_child(dev, &child);
+	for (device_find_first_child(udev->dev, &child);
 	     child;
 	     device_find_next_child(&child)) {
-		if (device_active(child))
-			show_info(child);
-	}
-}
-
-static int usb_device_info(void)
-{
-	struct udevice *bus;
-
-	for (uclass_first_device(UCLASS_USB, &bus);
-	     bus;
-	     uclass_next_device(&bus)) {
-		struct udevice *hub;
-
-		device_find_first_child(bus, &hub);
-		if (device_get_uclass_id(hub) == UCLASS_USB_HUB &&
-		    device_active(hub)) {
-			show_info(hub);
+		if (device_active(child)) {
+			udev = dev_get_parent_priv(child);
+			usb_show_info(udev);
 		}
 	}
-
-	return 0;
 }
 #endif
 
@@ -681,7 +662,7 @@ static int do_usb(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 	if (strncmp(argv[1], "inf", 3) == 0) {
 		if (argc == 2) {
 #ifdef CONFIG_DM_USB
-			usb_device_info();
+			usb_for_each_root_dev(usb_show_info);
 #else
 			int d;
 			for (d = 0; d < USB_MAX_DEVICE; d++) {