spi: cadence: Fix encoded CS mode

Signed-off-by: Paul Cercueil <paul.cercueil@analog.com>
ARM: dts: fmcadc3: Enable chip-select decoding

Signed-off-by: Paul Cercueil <paul.cercueil@analog.com>
iio: ad9467: Fix ad9234 configured as 16-bit instead of 12-bit

Signed-off-by: Paul Cercueil <paul.cercueil@analog.com>