perf sched timehist: Fix use of CPU list with summary option

Do not update thread stats or show idle summary unless CPU is in the
list of interest.

Fixes: c30d630d ("perf sched timehist: Add support for filtering on CPU")
Signed-off-by: David Ahern <dsahern@kernel.org>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Link: http://lore.kernel.org/lkml/20200817170943.1486-1-dsahern@kernel.org


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