tracing: Do not call kmem_cache_free() on allocation failure

There's no point calling it when _alloc() failed.

Link: http://lkml.kernel.org/r/1370585268-29169-1-git-send-email-namhyung@kernel.org



Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>