perf timechart: Implement IO mode

Currently, timechart records only scheduler and CPU events (task switches,
running times, CPU power states, etc); this commit adds IO mode which
makes it possible to record IO (disk, network) activity. In this mode
perf timechart will generate SVG with IO charts (writes, reads, tx, rx, polls).

Signed-off-by: Stanislav Fomichev <stfomichev@yandex-team.ru>
Acked-by: Namhyung Kim <namhyung@kernel.org>
Link: http://lkml.kernel.org/n/1404835423-23098-3-git-send-email-stfomichev@yandex-team.ru


Signed-off-by: Jiri Olsa <jolsa@kernel.org>