HID: add autodetection of multitouch devices

As mentioned by http://www.microsoft.com/whdc/device/input/DigitizerDrvs_touch.mspx
multitouch devices are those that have the input report HID_CONTACTID.

This patch detects this and unloads the generic-usb driver.

Signed-off-by: Benjamin Tissoires <benjamin.tissoires@enac.fr>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/include/linux/hid.h b/include/linux/hid.h
index 9cf8e7a..6fb743d 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -312,6 +312,7 @@
 #define HID_QUIRK_BADPAD			0x00000020
 #define HID_QUIRK_MULTI_INPUT			0x00000040
 #define HID_QUIRK_HIDINPUT_FORCE		0x00000080
+#define HID_QUIRK_MULTITOUCH			0x00000100
 #define HID_QUIRK_SKIP_OUTPUT_REPORTS		0x00010000
 #define HID_QUIRK_FULLSPEED_INTERVAL		0x10000000
 #define HID_QUIRK_NO_INIT_REPORTS		0x20000000