simpleperf: fix presubmit test after OpenCSD update.

We need to call TraceFormatterFrameDecoder::Init() after
https://github.com/Linaro/OpenCSD/commit/5a3a235359b0ed1ec25a12e84cec38fef08b1d6c.

Bug: 257478868
Test: run simpleperf_unit_test
Change-Id: I3ab03e1cfe4399d49913d16eb8012d27a18be794
1 file changed