Input: add driver for hampshire serial touchscreens

Adds support for Hampshire TSHARC serial touchscreens.  Implements
Hampshire's 4-byte communication protocol.

Signed-off-by: Adam Bennett <abennett72@gmail.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
diff --git a/include/linux/serio.h b/include/linux/serio.h
index 64b4730..b555256 100644
--- a/include/linux/serio.h
+++ b/include/linux/serio.h
@@ -196,5 +196,6 @@
 #define SERIO_TOUCHIT213	0x38
 #define SERIO_W8001	0x39
 #define SERIO_DYNAPRO	0x3a
+#define SERIO_HAMPSHIRE	0x3b
 
 #endif