HID: hid-multitouch: Switch to device groups

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 <[email protected]>
Acked-by: Benjamin Tissoires <[email protected]>
Signed-off-by: Jiri Kosina <[email protected]>