media: dt-bindings: adv7180: Introduce the 'reset-gpios' property

Introduce the 'reset-gpios' property to describe the GPIO that connects
to the ADV7180 reset pin.

Signed-off-by: Fabio Estevam <festevam@gmail.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>