fw/instrument: Fix compatibility with Python2
fw/instrument: Fix compatibility with Python2

The Python2 inspect module does not contain the `getfullargspec` method so call
the appropriate method depending on Python version.

ARM-software/workload-automation,lisatn/workload-automation,setrofim/workload-automation,setrofim/workload-automation,setrofim/workload-automation,lisatn/workload-automation,ARM-software/workload-automation,lisatn/workload-automation,ARM-software/workload-automation,ARM-software/workload-automation,setrofim/workload-automation,lisatn/workload-automation