USB: change dev_warn about missing reset-resume to dev_dbg

This patch changes a dev_warn() call in usbcore to dev_dbg().  It's
not necessary to warn about drivers missing a reset-resume callback,
since the reset-resume method is optional.
Signed-off-by: NAlan Stern <stern@rowland.harvard.edu>
CC: Clemens Ladisch <clemens@ladisch.de>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/core/driver.c

@@ -1179,8 +1179,8 @@ static int usb_resume_interface(struct usb_device *udev,
 						"reset_resume", status);
 		} else {
 			intf->needs_binding = 1;
-			dev_warn(&intf->dev, "no %s for driver %s?\n",
-					"reset_resume", driver->name);
+			dev_dbg(&intf->dev, "no reset_resume for driver %s?\n",
+					driver->name);
 		}
 	} else {
 		status = driver->resume(intf);