HID: wacom: Enable pad device for older Bamboo Touch tablets

Commit 862cf553 ("HID: wacom: Introduce a new WACOM_DEVICETYPE_PAD device_type")
neglected to set the WACOM_DEVICETYPE_PAD flag for older two-finger Bamboo
Touch tablets. Not only does this result in the pad device not appearing when
such a tablet is plugged in, but also causes a segfault when 'wacom_bpt_touch'
tries to send pad events. This patch adds the flag to resolve these issues.
Signed-off-by: Jason Gerecke <jason.gerecke@wacom.com>
Signed-off-by: Jiri Kosina <jkosina@suse.com>

drivers/hid/wacom_wac.c

@@ -2213,6 +2213,9 @@ void wacom_setup_device_quirks(struct wacom *wacom)
 			features->x_max = 4096;
 			features->y_max = 4096;
 		}
+		else if (features->pktlen == WACOM_PKGLEN_BBTOUCH) {
+			features->device_type |= WACOM_DEVICETYPE_PAD;
+		}
 	}
 
 	/*