Input: wacom - add a quirk for low resolution Bamboo devices

The Bamboo Touch reports a sub-screen resolution of 480x320.  The
signal-to-noise ratio is only about 100, so filtering is needed in
order to reduce the jitter to a usable level. However, the low
resolution leads to round-off errors in the EWMA filter, resulting in
extremely jerky pointer motion. This patch explicitly sets a higher
resolution for those devices, and tells this to the completion handler
via a low-resolution quirk.

Signed-off-by: Henrik Rydberg <rydberg@euromail.se>
Acked-by: Ping Cheng <pingc@wacom.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
diff --git a/drivers/input/tablet/wacom_wac.h b/drivers/input/tablet/wacom_wac.h
index a23d6a5..00ca015 100644
--- a/drivers/input/tablet/wacom_wac.h
+++ b/drivers/input/tablet/wacom_wac.h
@@ -40,6 +40,7 @@
 
 /* device quirks */
 #define WACOM_QUIRK_MULTI_INPUT		0x0001
+#define WACOM_QUIRK_BBTOUCH_LOWRES	0x0002
 
 /* largest reported tracking id */
 #define MAX_TRACKING_ID			0xfff