iio: accel: Add driver support for ADXL313

ADXL313 is a small, thin, low power, 3-axis accelerometer with high
resolution measurement up to +/-4g. It includes an integrated 32-level
FIFO and has activity and inactivity sensing capabilities.

Datasheet: https://www.analog.com/media/en/technical-documentation/data-sheets/ADXL313.pdf


Signed-off-by: Lucas Stankus <lucas.p.stankus@gmail.com>
Reviewed-by: Alexandru Ardelean <ardeleanalex@gmail.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Link: https://lore.kernel.org/r/d16e2d1967e46bb2b1024b6d23bc4889da77dc6b.1630523106.git.lucas.p.stankus@gmail.com


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