perf bench: Improve the 'perf bench mem memcpy' code readability

perf bench: Improve the 'perf bench mem memcpy' code readability

 - improve the readability of initializations
 - fix unnecessary double negations
 - fix ugly line breaks
 - fix other small details

Signed-off-by: Ingo Molnar <mingo@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1445241870-24854-2-git-send-email-mingo@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>