Input: wacom_serial4 - prepare for wacom USB moving to HID

wacom_wac.h will be moving to drivers/hid. Since we only need 3 definitions
from it let's simply copy them over.

Acked-by: Hans de Goede <[e-mail]>
Signed-off-by: Dmitry Torokhov <[e-mail]>

drivers/input/tablet/wacom_serial4.c

···
 #include <linux/serio.h>
 #include <linux/slab.h>
 #include <linux/string.h>
-#include "wacom_wac.h"
 
 MODULE_AUTHOR("Julian Squires <[e-mail]>, Hans de Goede <[e-mail]>");
 MODULE_DESCRIPTION("Wacom protocol 4 serial tablet driver");
···
 #define F_COVERS_SCREEN		0x01
 #define F_HAS_STYLUS2		0x02
 #define F_HAS_SCROLLWHEEL	0x04
+
+/* device IDs */
+#define STYLUS_DEVICE_ID	0x02
+#define CURSOR_DEVICE_ID	0x06
+#define ERASER_DEVICE_ID	0x0A
 
 enum { STYLUS = 1, ERASER, CURSOR };