iio: ad5755: fix spelling mistake "to" -> "too" and grammar plus formatting

There is a spelling mistake and grammar mistake in a dev_err
message. Fix it.

Also include Joe Perches' additional suggestions around:
* Missing newlines
* Excess braces
* Odd indentation
* Some grammar

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Reviewed-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Suggested-by: Joe Perches <joe@perches.com> # Additional cleanups etc.
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>