media: adv7604: fix HPD support for adv7611/12

For the adv7604 the hotplug detect pin is controlled through gpio pins from
the SoC, but the adv7611 and adv7612 control the hotplug detect pin
themselves.

But the driver had no support for this, so the HPD was always high, even
when changing the EDID. Add proper support for this to the driver.

Tested with an adv7612.

Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>