[enocean] Fix temperature values for D2_50 eep

[lovery]

Fixes #16974

There is a problem with parsing the data send from fan devices using EEP D2_50 (like Dimplex) When the value is with leading bite - 1 is converted to a number < 0 and then to unsined int which leads to a very big value for OutdorAirTempareture channel.

Looking at the code I thing this could also happen to other channels so I added a fix for them & 0xff