SurfaceFlinger: optimize frame rate override

On devices that frame rate override cannot be supported
as the device doesn't support refresh rates that are divisors of
each other, there is no point in trying to find a a frame rate override.

Bug: 170502573
Test: atest FrameRateOverrideHostTest
Change-Id: Idfce2573ee58fa695e81a00c85206990baad978e