Add a sysprop to control frame rate override

Adding 'ro.surface_flinger.enable_frame_rate_override' to control
whether frame rate override feature should be enabled or not.

Bug: 170502573
Bug: 176940141
Change-Id: Ida0e13f9a7c420f5f363d1feeacf882d8b76a8fa
Test: atest FrameRateOverrideHostTest
1 file changed