hwmon: (adm9240) Fix checkpatch issues

Fixed:
ERROR: do not use assignment in if condition
ERROR: that open brace { should be on the previous line
WARNING: please, no space before tabs
WARNING: simple_strtol is obsolete, use kstrtol instead
WARNING: simple_strtoul is obsolete, use kstrtoul instead

Modify multi-line comments to follow Documentation/CodingStyle.

Not fixed (false positive):
ERROR: Macros with multiple statements should be enclosed in a do - while loop

Signed-off-by: Guenter Roeck <linux@roeck-us.net>