HID: hid-multitouch: Switch to device groups

Switch the driver over to device group handling.  By adding the
HID_GROUP_MULTITOUCH group to hid-core, hid-generic will no longer
match multitouch devices.  By adding the HID_GROUP_MULTITOUCH entry to
the device list, hid-multitouch will match all unknown multitouch
devices, and udev will automatically load the module.

Since HID_QUIRK_MULTITOUCH never gets set, the special quirks handling
can be removed.  Since all HID MT devices have HID_DG_CONTACTID, they
can be removed from the hid_have_special_driver list.

With this patch, the unknown device ids are no longer NULL, so the code
is modified to check for the generic entry instead.

Signed-off-by: Henrik Rydberg <rydberg@euromail.se>
Acked-by: Benjamin Tissoires <benjamin.tissoires@gmail.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>
diff --git a/include/linux/hid.h b/include/linux/hid.h
index dd694fb..2c7a195 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -317,7 +317,6 @@
 #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
@@ -328,6 +327,7 @@
  * HID device groups
  */
 #define HID_GROUP_GENERIC			0x0001
+#define HID_GROUP_MULTITOUCH			0x0002
 
 /*
  * This is the global environment of the parser. This information is