tracing: make power tracer start/stop methods lighter weight
tracing: make power tracer start/stop methods lighter weight

The start/stop methods of a tracer should be able to be executed
in all contexts. This patch converts the power tracer to do so.

Signed-off-by: Steven Rostedt <9d183ff83abfec5c556edaf86a280a53916a11d8@redhat.com>

KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,TeamVee-Kanas/android_kernel_samsung_kanas,KristFoundation/Programs