Move chmod of /sys/kernel/debug/tracing to fix traceur.

This is a temporary fix, since we're still not sure exactly what the
bug is.

Bug: 62547086
Test: Built, flashed, and booted Marlin.  Verified that the file has
the correct permission and that traceur does not popup an error.

Change-Id: I43275e974a11754eca274f1b77d15cdd03a3b365