HID: wacom: Handle failing HID_DG_CONTACTMAX requests

Hardware may not respond to a request for the HID_DG_CONTACTMAX feature and
we should be tolerant of such a failure. This is especially true when using
hid-replay where the hardware doesn't exist, but also for devices attached
to a flaky bus. This patch increases the number of allowable retries to
match other calls to 'wacom_get_report' and also provides a fallback which
forces 'touch_max = 16' (enough for any Wacom device seen so far).

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