perf trace: Change syscall summary duration order

Switch duration order to minimum, average, maximum for the '--summary'
command line option because it's more natural to read.

Signed-off-by: Pekka Enberg <penberg@kernel.org>
Acked-by: David Ahern <dsahern@gmail.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Ingo Molnar <mingo@redhat.com>
Link: http://lkml.kernel.org/r/1384265410-12344-1-git-send-email-penberg@kernel.org


Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>