Add extra check for getAllValidTMPKeys()
Add extra check for getAllValidTMPKeys()

- We check that the sensor value is not zero. Some sensors while valid, report
  no tmp. For example, HEATSINK_0.
- Have readSMC() return data type and size. Will use this for safety checks
  higher up.

beltex/SMCKit,MagicInstall/SMCKit