SurfaceFlinger: define a known frame rates list

Keep a list of known frame rates that would be used when we calculated
heuristically the frame rate of a layer. This keeps the signal to the
algorithm that chooses the refresh rate steady and avoid strange
frame rates like 57.2 due to inconsistent presentation timestamps.

Bug: 157540021
Test: adb shell /data/nativetest64/libsurfaceflinger_unittest/libsurfaceflinger_unittest
Change-Id: I97a24b74605256646e9b8444bd9f3818fe0a4a2a