[WHY]
Some games experience low FPS issues when FreeSync is on and VSync is
toggled to half refresh rate.

[HOW]
First create a function to determine workaround conditions, which is
when we detect 2 or more VSync interrupts between flips and a very short
VSync to flip interval. We do the workaround during VSync interrupts and
set the v_total_max and min to nominal. We also cleanup after we exit
the game.
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Reviewed-by: Anthony Koo <Anthony.Koo@amd.com>
Reviewed-by: Aric Cyr <Aric.Cyr@amd.com>
Acked-by: Tom Chung <chiahsuan.chung@amd.com>
Signed-off-by: Angus Wang <Angus.Wang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>