staging: iio: cdc: ad7746: remove ordinary comments

Remove ordinary comments about typical driver structure.
Also align one comment with wrong indentation.

Signed-off-by: Lucas Stankus <lucas.p.stankus@gmail.com>
Link: https://lore.kernel.org/r/e93e5efb19cee53546a339c1caf1ab344e9ff282.1621786036.git.lucas.p.stankus@gmail.com


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