hwmon: (abx500) Fix format string warnings

Fixed the following warnings (reported by cppcheck):
[drivers/hwmon/abx500.c:224]: (warning) %ld in format string (no. 1)
requires 'long' but the argument type is 'unsigned long'.
[drivers/hwmon/abx500.c:233]: (warning) %ld in format string (no. 1)
requires 'long' but the argument type is 'unsigned long'.
[drivers/hwmon/abx500.c:242]: (warning) %ld in format string (no. 1)
requires 'long' but the argument type is 'unsigned long'.

Signed-off-by: Asaf Vertz <asaf.vertz@tandemg.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>