simpleperf: Fix setting max sample frequency

When users want to record with a high sample frequency, simpleperf
needs to raise limit of perf_event_max_sample_rate in /proc. This
logic is broken because of forgetting to set max_sample_freq_.

Bug: 397098552
Test: run simpleperf manually
Change-Id: I1d48c28324464a90a57981b414dbef58f6d71dda
1 file changed