perf kvm stat live: Mark events as (x86 only) in help output

perf kvm stat live: Mark events as (x86 only) in help output

The mmio and ioport events are useful only on x86.

Signed-off-by: Alexander Yarygin <yarygin@linux.vnet.ibm.com>
Acked-by: David Ahern <dsahern@gmail.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Link: http://lkml.kernel.org/r/1418218090-20718-1-git-send-email-borntraeger@de.ibm.com
Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>