tracefs not debugfs

Test:   Device boots
        Can take photos
        Run "adb shell atrace -c -b 16000 -t 5 gfx" without root and check produces
        output
        Run "python systrace.py view gfx freq sched am wm dalvik
        binder_driver" from external/chromium-trace after adb root and
        check populated
Bug: 31856701
Change-Id: Ic319f8a0a3e395efa7ee8ba33a868ac55cb44fe4

private/file_contexts

@@ -436,12 +436,12 @@
 # debugfs files
 #
 /sys/kernel/debug/mmc0(/.*)?                            u:object_r:debugfs_mmc:s0
-/sys/kernel/debug/tracing(/.*)?				u:object_r:debugfs_tracing:s0
-/sys/kernel/debug/tracing/trace_marker			u:object_r:debugfs_trace_marker:s0
-/sys/kernel/debug/tracing/instances(/.*)?		u:object_r:debugfs_tracing_instances:s0
-/sys/kernel/debug/tracing/instances/wifi/free_buffer	u:object_r:debugfs_wifi_tracing:s0
-/sys/kernel/debug/tracing/instances/wifi/trace		u:object_r:debugfs_wifi_tracing:s0
-/sys/kernel/debug/tracing/instances/wifi/tracing_on	u:object_r:debugfs_wifi_tracing:s0
+/sys/kernel(/debug)?/tracing(/.*)?			u:object_r:debugfs_tracing:s0
+/sys/kernel(/debug)?/tracing/trace_marker		u:object_r:debugfs_trace_marker:s0
+/sys/kernel(/debug)?/tracing/instances(/.*)?		u:object_r:debugfs_tracing_instances:s0
+/sys/kernel(/debug)?/tracing/instances/wifi/free_buffer	u:object_r:debugfs_wifi_tracing:s0
+/sys/kernel(/debug)?/tracing/instances/wifi/trace	u:object_r:debugfs_wifi_tracing:s0
+/sys/kernel(/debug)?/tracing/instances/wifi/tracing_on	u:object_r:debugfs_wifi_tracing:s0
 
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 # asec containers