[kineto] set the correct device id for GenericTraceActivity
Summary: while merging ClientTraceActivity and GenericTraceActivity, we accidentally adopted CTA's behavior of returning process id over its `device`. This causes GTA to show up in CPU timeline rather than associated GPU's
Test Plan:
before
https://www.internalfb.com/intern/perfdoctor/trace_view?filepath=tree%2Ftraces%2Fdynocli%2F0%2F1620113910%2F127.0.0.1%2Flibkineto_activities_1270242.json.gz&bucket=gpu_traces
{F613233496}
after
https://www.internalfb.com/intern/perfdoctor/trace_view?filepath=tree%2Ftraces%2Fdynocli%2F0%2F1620115859%2F127.0.0.1%2Flibkineto_activities_1511899.json.gz&bucket=gpu_traces
{F613231643}
Reviewed By: gdankel
Differential Revision: D28196723
fbshipit-source-id: eb8330c14e7c43a470bb4df4811b80754d96535b
