usb: gadget: Quieten gadget config message

On a system that often re-configures a USB gadget device the kernel log
is filled with:

  configfs-gadget gadget: high-speed config #1: c

Reduce the verbosity of this print to debug.
Signed-off-by: Joel Stanley <joel@jms.id.au>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/gadget/composite.c

@@ -794,9 +794,9 @@ static int set_config(struct usb_composite_dev *cdev,
 		result = 0;
 	}
 
-	INFO(cdev, "%s config #%d: %s\n",
-	     usb_speed_string(gadget->speed),
-	     number, c ? c->label : "unconfigured");
+	DBG(cdev, "%s config #%d: %s\n",
+	    usb_speed_string(gadget->speed),
+	    number, c ? c->label : "unconfigured");
 
 	if (!c)
 		goto done;