framework/plugin: Fix clearing of loaded plugin
framework/plugin: Fix clearing of loaded plugin

`self.plugins` should be a dictionary and when being cleared was being
reinitialized as a list.

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