iio: accel: bma400: Replace bit shifts with FIELD_PREP() and FIELD_GET()

iio: accel: bma400: Replace bit shifts with FIELD_PREP() and FIELD_GET()

set_* functions involve left shift of param values into respective
register fields before writing to register. Similarly get_* functions
involve right shift to extract values from the respective bit fields.
Replace these explicit shifting statements with standard kernel style
macros FIELD_GET() and FIELD_PREP().

Signed-off-by: Akshay Jindal <akshayaj.lkd@gmail.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>