Let the default Atrace HAL support /sys/kernel/tracing

With this change, atrace HAL will look for tracefs in
/sys/kernel/tracing first and /sys/kernel/debug/tracing second.

Test: systrace
Bug: 185427606
Change-Id: Iccc5af92db222dc422a527c14b1f2fb7bc4e7746
3 files changed