HID: wacom: generic: Recognize WACOM_HID_WD_PEN as a type of pen collection

HID: wacom: generic: Recognize WACOM_HID_WD_PEN as a type of pen collection

The WACOM_PEN_FIELD macro is used to determine if a given HID field should be
associated with pen input. This field includes several known collection types
that Wacom pen data is contained in, but the WACOM_HID_WD_PEN application
collection type is notably missing. This can result in fields within this
kind of collection being completely ignored by the `wacom_usage_mapping`
function, preventing the later '*_event' functions from being notified about
changes to their value.

Fixes: 3b2c38fe77 ("HID: wacom: generic: Support and use 'Custom HID' mode and usages")
Fixes: 839402503c ("HID: wacom: generic: add vendor defined touch")
Cc: stable@vger.kernel.org
Reviewed-by: Ping Cheng <ping.cheng@wacom.com>
Reviewed-by: Benjamin Tissoires <benjamin.tissoires@redhat.com>
Signed-off-by: Jason Gerecke <jason.gerecke@wacom.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>