iio: imu: inv_icm42600: add accelerometer IIO device

Add IIO device for accelerometer sensor with data polling
interface.
Attributes: raw, scale, sampling_frequency, calibbias.

Accelerometer in low noise mode.

Signed-off-by: Jean-Baptiste Maneyrol <jmaneyrol@invensense.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>