Adding binding documentation for Texas Instruments ADS8688 ADC.
Signed-off-by: NSean Nyekjaer <sean.nyekjaer@prevas.dk>
Reviewed-by: NMartin Hundebøll <martin.hundeboll@prevas.dk>
Acked-by: NRob Herring <robh@kernel.org>
Signed-off-by: NJonathan Cameron <jic23@kernel.org>