Several fixes for the Puzzle WT61P803 hwmon driver were needed to make
it behave well as thermal cooling device:
- wire-up cooling device with OF node in device tree
- properly parse cooling-levels (u32 with range check vs. u8)
- actually use cooling-levels
- keep current state and only write to uC if state has changed
(avoids flooding the uC with commands which will result in uC crashing)
Signed-off-by: Daniel Golle <daniel@makrotopia.org>