drm/amdgpu: Fix max_vblank_count value for current display engines

The value was much too low, which could cause the userspace visible
vblank counter to move backwards when the hardware counter wrapped
around.

Ported from radeon commit:
b0b9bb4dd51f396dcf843831905f729e74b0c8c0

Reviewed-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Jammy Zhou <Jammy.Zhou@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
1 file changed