[SystemInfo] Fixed SIM callback error and type mismatch error

The old design principle was if sim_get_** API's return value didn't equal SIM_ERROR_NONE, 
we return an error callback. However, if the SIM status is not READY, other attributes won't be 
gotten (sim_get_** won't return SIM_ERROR_NONE). So, here, we add sim_get_** API return 
value's checking. If the return value equals SIM_ERROR_NOT_AVAILABLE, we reset the according
 attribute's value to empty and return true.