drm/amd/powerplay/smu11: add secure board check function (v2)

To determine whether the board is secure or not.

v2: rebase (Alex)

Signed-off-by: Tao Zhou <tao.zhou1@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Kevin Wang <kevin1.wang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>