HID: wacom: Do not add suffix to name of devices with an unknown type

The naming logic currently assumes that all devices will be a pen, finger,
or pad. Though this has historically been the case, the new HID_GENERIC
catch-all may cause us to probe devices with Wacom's 056A VID which aren't
any of these types (e.g. the "Cintiq 24HDT Monitor Control"). This patch
updates the logic so that no suffix will be added to the device name if
the device type is unknown.

Signed-off-by: Jason Gerecke <jason.gerecke@wacom.com>
Reviewed-by: Ping Cheng <pingc@wacom.com>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>