change processor_temperature icon (#52256)
change processor_temperature icon (#52256)

* change processor_temperature icon

to indicate the temperature, using "mdi:thermometer"

* add DEVICE_CLASS_TEMPERATURE,

* add None for icon

* remove Icon from Last boot

since it uses the device_class already
rohitranjan1991/home-assistant,jawilson/home-assistant,w1ll1am23/home-assistant,rohitranjan1991/home-assistant,mezz64/home-assistant,aronsky/home-assistant,GenericStudent/home-assistant,toddeye/home-assistant,lukas-hetzenecker/home-assistant,sander76/home-assistant,toddeye/home-assistant,jawilson/home-assistant,w1ll1am23/home-assistant,FreekingDean/home-assistant,rohitranjan1991/home-assistant,Danielhiversen/home-assistant,Danielhiversen/home-assistant,home-assistant/home-assistant,nkgilley/home-assistant,FreekingDean/home-assistant,home-assistant/home-assistant,GenericStudent/home-assistant,mezz64/home-assistant,sander76/home-assistant,nkgilley/home-assistant,aronsky/home-assistant,lukas-hetzenecker/home-assistant