Re-use the therm-exported fan structure with only two minor modifications:
- pwm_freq: u16 -> u32;
- add fan_type (toggle or PWM)

v2:
- Do not memset the table to 0 as it erases the pre-set default values
Signed-off-by: Martin Peres <martin.peres@free.fr>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>