atrace: Add sched_process_free trace event

sched/sched_process_free trace event was missing from atrace - an
oversight caught in the process of removing other permission bits from
tracefs.

Bug: 208892266
Bug: 209513178
Test: Manual
Change-Id: Ib208130671e943e409331d51efb8765cc59f0b4a
1 file changed