media: i2c: adv7180: fix adv7280 BT.656-4 compatibility

media: i2c: adv7180: fix adv7280 BT.656-4 compatibility

Captured video would be out of sync when using the adv7280 with
the BT.656-4 protocol. Certain registers (0x04, 0x31, 0xE6) had to
be configured properly to ensure BT.656-4 compatibility.

An error in the adv7280 reference manual suggested that EAV/SAV mode
was enabled by default, however upon inspecting register 0x31, it was
determined to be disabled by default.

[fabio: Introduce "adv,force-bt656-4" to not affect the existing users]
[hverkuil: fix a small checkpatch alignment warning]

Signed-off-by: Matthew Michilot <matthew.michilot@gmail.com>
Reviewed-by: Tim Harvey <tharvey@gateworks.com>
Signed-off-by: Fabio Estevam <festevam@gmail.com>
Tested-by: Tim Harvey <tharvey@gateworks.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>