iio: accel: adxl372: Fix/remove limitation for FIFO samples

iio: accel: adxl372: Fix/remove limitation for FIFO samples

Currently, the driver sets the FIFO_SAMPLES register with the number of
sample sets (maximum of 170 for 3 axis data, 256 for 2-axis and 512 for
single axis). However, the FIFO_SAMPLES register should store the number
of samples, regardless of how the FIFO format is configured.

Signed-off-by: Stefan Popa <stefan.popa@analog.com>
Fixes: f4f55ce38e5f ("iio:adxl372: Add FIFO and interrupts support")
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>