perf tools: Do not check debugfs MAGIC for tracing files

It's rather strange to be checking the debugfs MAGIC number for the
tracing directory. A system admin may want to have a custom set of
events to trace and it should be allowed to let the admin make a temp
file (even for tracing virtual boxes, this is useful).

Also with the coming tracefs, the files may not even be under debugfs,
so checking the debugfs MAGIC number is pointless.

Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Masami Hiramatsu <masami.hiramatsu.pt@hitachi.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/r/20150202193552.546175764@goodmis.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>