RADV Vulkan Driver Lands FreeSync/Adaptive-Sync For Mesa 19.1

While on the kernel-side there has been FreeSync support with the AMDGPU DRM driver since Linux 5.0 and for the OpenGL driver with RadeonSI there has been this functionality in Mesa 19.0 when paired with a supported kernel, the Mesa Radeon Vulkan driver has missed out on this action until now. But landing just in time for the Mesa 19.1 feature freeze is now the FreeSync/Adaptive-Sync enablement for RADV...