iio: proximity: as3935: remove triggered buffer processing

Triggered buffers shouldn't return processed data, and the respective
conversion was overflowing the defined .realbits for the channel.

Cc: george.mccollister@gmail.com
Signed-off-by: Matt Ranostay <mranostay@gmail.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>