HID: wacom: Use correct report to query pen ID from INTUOSHT2 devices

Unlike other tablets which are compatible with the wacom_intuos_irq handler,
INTUOSHT2 devices provide pen ID with report ID 8 instead of 5. To ensure
wacom_intuos_schedule_prox_event works as intended for these tablets, we
must be sure it uses the correct report ID in this case.

Signed-off-by: Jason Gerecke <jason.gerecke@wacom.com>
Signed-off-by: Jiri Kosina <jkosina@suse.cz>