[low-power] enhance mCslFrameRequestAheadUs calculation for RCP
#93
| Job | Run time |
|---|---|
| 3m 17s | |
| 12m 35s | |
| 31m 22s | |
| 9m 50s | |
| 11m 7s | |
| 9m 32s | |
| 10m 59s | |
| 11m 17s | |
| 10m 25s | |
| 27s | |
| 1h 50m 51s |