commit 6b8812eb upstream.

This is a port of radeon commit:
3d2d98ee
drm/radeon: use drm_mode_vrefresh() rather than mode->vrefresh
to amdgpu.
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>