tracing: Prevent wasting time evaluating parameters in trace_preempt_on/off
tracing: Prevent wasting time evaluating parameters in trace_preempt_on/off

This fixes spending time for evaluating parameters in trace_preempt_on/off when
the tracer config is off.

The patch mainly inspired by Steven Rostedt, thanks Steven.

Link: http://lkml.kernel.org/r/4FA73510.7070705@samsung.com

Cc: Ingo Molnar <9dbbbf0688fedc85ad4da37637f1a64b8c718ee2@redhat.com>
Cc: Frederic Weisbecker <e8a1bf9163cb25e93cfd6540f223b3872ea7ee55@gmail.com>
Cc: Peter Zijlstra <645ca7d3a8d3d4f60557176cd361ea8351edc32b@chello.nl>
Cc: Paul Turner <56b59ac50e86208fd62726b53c1d890b9a8ff058@google.com>
Cc: Thomas Gleixner <00e4cf8f46a57000a44449bf9dd8cbbcc209fd2a@linutronix.de>
Cc: Hidetoshi Seto <934438d7103b8cf842e8f6117400110cee66898a@jp.fujitsu.com>
Cc: Paul E. McKenney <1e0ce936bb9b355d257bf5790d2513c3f28be22b@linux.vnet.ibm.com>
Cc: Josh Triplett <c028c213ed5efcf30c3f4fc7361dbde0c893c5b7@joshtriplett.org>
Signed-off-by: Minho Ban <f18655baf81d76a1a8e875b960f9e4b628a81e0e@samsung.com>
Signed-off-by: Steven Rostedt <43232e92d70cc7aa53504ad0397085ee47bad87f@goodmis.org>

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