iio: accel: adxl355: Add triggered buffer support

Provide a way for continuous data capture by setting up buffer support. The
data ready signal exposed at the DRDY pin of the ADXL355 is exploited as
a hardware interrupt which triggers to fill the buffer.

Signed-off-by: Puranjay Mohan <puranjay12@gmail.com>
Link: https://lore.kernel.org/r/20210903184312.21009-3-puranjay12@gmail.com


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