power: supply: ab8500: clean up warnings found by checkpatch

Clean up a handful of checkpatch warnings:
 - static const char * array should probably be static const char * const
 - function arguments should have identifier names
 - else should follow close brace '}'
 - suspect code indent for conditional statements
 - unnecessary parentheses in an if condition
 - avoid multiple line dereference
 - remove debug showing function execution, ftrace can trace these better
 - prefer 'long' over 'long int' as the int is unnecessary

Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>