simpleperf: Fix calculation of lost sample percentage in userspace

simpleperf_record_count_ includes cut stack samples. So if we add
simpleperf_record_count_ and userspace_lost_cut_samples, we add
cut stack samples twice.

Bug: none
Test: run simpleperf manually
Change-Id: Ie84c32134924f217d601f9439b6cd836f0103928
1 file changed