perf ui progress: Add size info into progress bar

perf ui progress: Add size info into progress bar

Adding the size values '[current/total]' into progress bar, to show more
detailed progress of data reading.

Adding new ui_progress__init_size function to specify we want to display
the size.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: David Ahern <dsahern@gmail.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20170908120510.22515-5-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>