perf time-utils: Make perf_time__parse_for_ranges() more logical

Explicit time ranges never contain a percent sign whereas percentage
ranges always do, so it is possible to call the correct parser.

Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Link: http://lkml.kernel.org/r/20190604130017.31207-18-adrian.hunter@intel.com


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