[media] adv7511: disable register reset by HPD

Whenever the hotplug pin is pulled low the chip resets a whole bunch
of registers. It turns out that this can be turned off on the adv7511.
Do so, as this 'feature' introduces race conditions in setting up
registers, particular when the hotplug pin bounces a lot.

Signed-off-by: Martin Bugge <marbugge@cisco.com>
Signed-off-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Mauro Carvalho Chehab <m.chehab@samsung.com>