kmemtrace: Print binary output only if 'bin' option is set

Currently by default the output of kmemtrace is binary format instead
of human-readable output.

This patch makes the following changes:

  - We'll see human-readable output by default
  - We'll see binary output if 'bin' option is set

Note: you may probably need to explicitly disable context-info binary
      output:

	# echo 0 > options/context-info
	# echo 1 > options/bin
	# cat trace_pipe

v2:
- use %pF to print call_site

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Pekka Enberg <penberg@cs.helsinki.fi>
Acked-by: Eduard - Gabriel Munteanu <eduard.munteanu@linux360.ro>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <4A4DD0A0.5060500@cn.fujitsu.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>