HID: hid-multitouch: Only match MT interfaces

All known hid-multitouch devices currently match any device group.
However, some devices present interfaces belonging to different groups,
resulting in a race between the hid-generic and hid-multitouch modules.
This patch narrows the MT device list to match only HID_GROUP_MULTITOUCH,
which solves the problem.

As an exception, the USB_DEVICE_ID_CYPRESS_TRUETOUCH panel is not
modified, in order to suppress the unwanted extra interfaces of the
device.

Reported-by: Benjamin Tissoires <benjamin.tissoires@gmail.com>
Signed-off-by: Henrik Rydberg <rydberg@euromail.se>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@enac.fr>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>