Merge "simpleperf: update doc for --trace-offcpu." am: 55c90adf61 am: 2b1a3c00a8 am: 0566f4fff5

Original change: https://android-review.googlesource.com/c/platform/system/extras/+/1901930

Change-Id: Iaed1c40c729c8a2beedc22f43a71f5afad5a4f5f