Fix selinux warning on tracefs systems

restorecon_recursive doesn't traverse filesystem boundaries. On
tracefs systems, tracing is a separate filesystem, so restorecon
this as well

Bug: 30963384
Test: Boot hikey, and check that there are no debugfs_tracing denials in dmesg
Change-Id: I24abd3ad80d2cfdab4f64fecee799fc0c24ed238