perf top: Add intel_idle to the skip list

TODO: Accrue the cycles in the skip_list to an idle total, and show this
on the 'top' UI, as suggested by Steven.

Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Link: http://lkml.kernel.org/n/tip-9nfecmgghgl5747rjxqpc28f@git.kernel.org


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