hwmon: (atxp1) Fix checkpatch issues

hwmon: (atxp1) Fix checkpatch issues

Fixed:
ERROR: code indent should use tabs where possible
ERROR: do not use assignment in if condition
ERROR: else should follow close brace '}'
ERROR: "foo * bar" should be "foo *bar"
WARNING: braces {} are not necessary for single statement blocks
WARNING: line over 80 characters
WARNING: please, no space before tabs
WARNING: please, no spaces at the start of a line
WARNING: simple_strtoul is obsolete, use kstrtoul instead

Modify multi-line comments to follow Documentation/CodingStyle.

Cc: Sebastian Witt <se.witt@gmx.net>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>