i8k_get_fan_speed
val = i8k_get_fan_speed(data, val);
left_speed = i8k_get_fan_speed(data, I8K_FAN_LEFT); /* 580 µs */
right_speed = i8k_get_fan_speed(data, I8K_FAN_RIGHT); /* 580 µs */
ret = i8k_get_fan_speed(data, channel);