iio: accel: adxl372: Perform a reset at start up

We need to perform a reset a start up to make sure that the chip is in a
consistent state. This reset also disables all the interrupts which
should only be enabled together with the iio buffer. Not doing this, was
sometimes causing unwanted interrupts to trigger.

Signed-off-by: Stefan Popa <stefan.popa@analog.com>
Fixes: f4f55ce3

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