HID: wacom: PAD is independent with pen/touch

PAD can be on pen interface (Intuos Pro and Cintiq series) or touch
interface (Bamboo PT and Intuos PT series) or its own interface
(Bamboo pen-only and Intuos Pen M/S). We need to mark it independently.

Signed-off-by: Ping Cheng <pingc@wacom.com>
Reviewed-by:  Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/drivers/hid/wacom_wac.h b/drivers/hid/wacom_wac.h
index 0f0b85e..128cbb3 100644
--- a/drivers/hid/wacom_wac.h
+++ b/drivers/hid/wacom_wac.h
@@ -183,6 +183,7 @@
 	struct input_dev *input;
 	struct input_dev *pad_input;
 	bool input_registered;
+	bool pad_registered;
 	int pid;
 	int battery_capacity;
 	int num_contacts_left;