thermal: testing: Initialize some variables annoteded with _free()

In the Linux kernel, the following vulnerability has been resolved:

thermal: testing: Initialize some variables annoteded with _free()

Variables annotated with __free() need to be initialized if the function

can return before they get updated for the first time or the attempt to

free the memory pointed to by them upon function return may crash the

kernel.

Fix this issue in some places in the thermal testing code.