iio: imu: adis16475: Create push single sample API

Create push single sample API reposnsible for pushing a single
sample into the buffer.
This is a preparation patch for FIFO support where more than
one sample has to be pushed in the trigger handler.

Reviewed-by: Nuno Sa <nuno.sa@analog.com>
Signed-off-by: Ramona Gradinariu <ramona.bolboaca13@gmail.com>
Link: https://lore.kernel.org/r/20240527142618.275897-5-ramona.bolboaca13@gmail.com


Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>