usb: gadget: bcm63xx_udc: create debugfs directory under usb root

Now the USB gadget subsystem can use the USB debugfs root directory,
so move it's directory from the root of the debugfs filesystem into
the root of usb
Signed-off-by: Chunfeng Yun <chunfeng.yun@mediatek.com>
Link: https://lore.kernel.org/r/1573541519-28488-8-git-send-email-chunfeng.yun@mediatek.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/gadget/udc/bcm63xx_udc.c

@@ -2248,7 +2248,7 @@ static void bcm63xx_udc_init_debugfs(struct bcm63xx_udc *udc)
 	if (!IS_ENABLED(CONFIG_USB_GADGET_DEBUG_FS))
 		return;
 
-	root = debugfs_create_dir(udc->gadget.name, NULL);
+	root = debugfs_create_dir(udc->gadget.name, usb_debug_root);
 	udc->debugfs_root = root;
 
 	debugfs_create_file("usbd", 0400, root, udc, &bcm63xx_usbd_dbg_fops);