HID: wacom: correct touch resolution x/y typo

This affects the 2nd-gen Intuos Pro Medium and Large
when using their Bluetooth connection.

Fixes: 4922cd26 ("HID: wacom: Support 2nd-gen Intuos Pro's Bluetooth classic interface")
Cc: <stable@vger.kernel.org> # v4.11+
Signed-off-by: Aaron Armstrong Skomra <aaron.skomra@wacom.com>
Reviewed-by: Jason Gerecke <jason.gerecke@wacom.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>