hwmon: (pmbus/core) Fix various coding style issues

Checkpatch reports bad multi-line comments, bad multi-line alignments,
missing blank lines after variable declarations, unnecessary empty lines,
unnecessary spaces, and unnecessary braces. Fix most of the reported
problems except for some multi-line alignment problems.

Reviewed-by: Tzung-Bi Shih <tzungbi@kernel.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>