dt-bindings: iio: accel: bosch,bma220 setup SPI clock mode

dt-bindings: iio: accel: bosch,bma220 setup SPI clock mode

Assert CPOL for a high-idle clock signal and CPHA for sampling on the
trailing (rising) edge.

Quoting from the datasheet:

 "During the transitions on CSB, SCK must be high. SDI and SDO are driven
 at the falling edge of SCK and should be captured at the rising edge of
 SCK."

The sensor does not function with the default SPI clock mode.

Fixes: 7dbd479425d2 ("dt-bindings:iio:accel:bosch,bma220 device tree binding documentation")
Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Signed-off-by: Petre Rodan <petre.rodan@subdimension.ro>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>