[unifi] Detect all PoE ports, and set PoE thing offline if no data could be found...

[unifi] Detect all PoE ports, and set PoE thing offline if no data could be found (#13455)

* [unifi] Set PoE thing offline if no data could be found

This would better reflect the PoE thing status if there is a problem with either the data from the api or a configuration problem (like invalid port number).

* [unifi] Fix bug to detect PoE ports when first port is not PoE port

The binding assumed either all ports or no ports were PoE, and asssumed if port 0 was not PoE none was PoE.
However, some switches have ports starting at port 5 to be PoE. Therefor changed code to just test each port if it is PoE.

Signed-off-by: Hilbrand Bouwkamp <hilbrand@h72.nl>