This bit is marked as reserved in the ADV Hardware Reference Manual.

Resetting this bit seems to cause increased video noise. Setting this
bit according to the Hardware Reference Manual reduces the video noise
immediately.
Signed-off-by: NBenjamin Marty <info@benjaminmarty.ch>
Reviewed-by: NDave Stevenson <dave.stevenson@raspberrypi.com>
Reviewed-by: NKieran Bingham <kieran.bingham+renesas@ideasonboard.com>
Tested-by: NDave Stevenson <dave.stevenson@raspberrypi.com>
Signed-off-by: NHans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: NMauro Carvalho Chehab <mchehab@kernel.org>