Add bindings documentation for stm32 CEC driver.
Signed-off-by: NBenjamin Gaignard <benjamin.gaignard@linaro.org>
Acked-by: NRob Herring <robh@kernel.org>
Signed-off-by: NHans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: NMauro Carvalho Chehab <mchehab@s-opensource.com>