Input: add support for Wacom W8001 penabled serial touchscreen

The Wacom W8001 sensor is a sensor device (uses electromagnetic
resonance) and it is interfaced via its serial microcontroller
to the host.

Signed-off-by: Jaya Kumar <jayakumar.lkml@gmail.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
diff --git a/include/linux/serio.h b/include/linux/serio.h
index 25641d9..1bcb357 100644
--- a/include/linux/serio.h
+++ b/include/linux/serio.h
@@ -213,5 +213,6 @@
 #define SERIO_ZHENHUA	0x36
 #define SERIO_INEXIO	0x37
 #define SERIO_TOUCHIT213	0x37
+#define SERIO_W8001	0x39
 
 #endif