staging: iio: accel: adis16220: Improve readability

Lines with #define interlaced with comment lines making a mess.

Separate groups of #define-comment with blank lines.
Separate section title comments with blank lines.

Signed-off-by: Svetlana Orlik <sveta.orlik.code@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>