hwmon: (ibmpex) Initialize sysfs attributes

Initialize dynamically allocated sysfs attributes before device_create_file()
call to suppress lockdep_init_map() warning if lockdep debugging is enabled.

Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>
Acked-by: Jean Delvare <khali@linux-fr.org>
Cc: stable@kernel.org # 2.6.34+