perf kvm stat: Properly show submicrosecond times

For lots of exits the min time (and sometimes max) is 0 or 1. Lets
increase the accurancy similar to what the average field alread does.

Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Acked-by: David Ahern <dsahern@gmail.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Paolo Bonzini <pbonzini@redhat.com>
Cc: kvm@vger.kernel.org
Link: http://lkml.kernel.org/r/1406805231-10675-2-git-send-email-borntraeger@de.ibm.com


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