dm: usb: Do not assume that first child is always a hub

On some single port (otg) controllers there is no emulated root hub, so
the first child (if any) may be one of: UCLASS_MASS_STORAGE,
UCLASS_USB_DEV_GENERIC or UCLASS_USB_HUB.

All three of these (and in the future others) are suitable for our
purposes, remove the check for the device being a hub, and add a check to
deal with the fact that there may be no child-dev.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Simon Glass <sjg@chromium.org>

common/cmd_usb.c

@@ -630,12 +630,11 @@ static int do_usb(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
 		     bus;
 		     uclass_next_device(&bus)) {
 			struct usb_device *udev;
-			struct udevice *hub;
+			struct udevice *dev;
 
-			device_find_first_child(bus, &hub);
-			if (device_get_uclass_id(hub) == UCLASS_USB_HUB &&
-			    device_active(hub)) {
-				udev = dev_get_parentdata(hub);
+			device_find_first_child(bus, &dev);
+			if (dev && device_active(dev)) {
+				udev = dev_get_parentdata(dev);
 				usb_show_tree(udev);
 			}
 		}

drivers/usb/host/usb-uclass.c

@@ -303,14 +303,14 @@ static struct usb_device *find_child_devnum(struct udevice *parent, int devnum)
 
 struct usb_device *usb_get_dev_index(struct udevice *bus, int index)
 {
-	struct udevice *hub;
+	struct udevice *dev;
 	int devnum = index + 1; /* Addresses are allocated from 1 on USB */
 
-	device_find_first_child(bus, &hub);
-	if (device_get_uclass_id(hub) == UCLASS_USB_HUB)
-		return find_child_devnum(hub, devnum);
+	device_find_first_child(bus, &dev);
+	if (!dev)
+		return NULL;
 
-	return NULL;
+	return find_child_devnum(dev, devnum);
 }
 
 int usb_post_bind(struct udevice *dev)