usb: gadget: udc: gr_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/1574232183-5760-3-git-send-email-chunfeng.yun@mediatek.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/gadget/udc/gr_udc.c

@@ -29,6 +29,7 @@
 #include <linux/list.h>
 #include <linux/interrupt.h>
 #include <linux/device.h>
+#include <linux/usb.h>
 #include <linux/usb/ch9.h>
 #include <linux/usb/gadget.h>
 #include <linux/dma-mapping.h>
@@ -208,7 +209,7 @@ static void gr_dfs_create(struct gr_udc *dev)
 {
 	const char *name = "gr_udc_state";
 
-	dev->dfs_root = debugfs_create_dir(dev_name(dev->dev), NULL);
+	dev->dfs_root = debugfs_create_dir(dev_name(dev->dev), usb_debug_root);
 	debugfs_create_file(name, 0444, dev->dfs_root, dev, &gr_dfs_fops);
 }