simpleperf: add --interval-only-values in stat cmd.

This is to print numbers of events happened in each interval.

Also avoid the last summary print for --interval option.

Bug: http://b/76117442
Test: run simpleperf_unit_test.

Change-Id: Ic139c2e85a6141508cae40a8e6438c28872d88d5
2 files changed