HID: debugfs: wake up reading tasks upon event

Some devices poke the hid core in a way that causes hid_debug_event to
be called, while never calling hid_dump_input. Without this wakeup
addition, tasks reading for hid events through debugfs may never see any
events. It may be that a well written driver doesn't cause this, but
then what's the point of debugfs?
Signed-off-by: Chase Douglas <chase.douglas@canonical.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>

drivers/hid/hid-debug.c

@@ -570,6 +570,8 @@ void hid_debug_event(struct hid_device *hdev, char *buf)
 				buf[i];
 		list->tail = (list->tail + i) % HID_DEBUG_BUFSIZE;
         }
+
+	wake_up_interruptible(&hdev->debug_wait);
 }
 EXPORT_SYMBOL_GPL(hid_debug_event);