The hardware timestamping implementation has been reported as not
working correctly on at least the Logitech C920. Until this can be
fixed, disable it by default.
Reported-by: Peter Rabbitson <rabbit@rabbit.us>
Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@osg.samsung.com>