Reset GFX RAS status registers.

v2: fix typo in title.
    remove xcp operation.
v3: change instance from 0 to xcc_id for register access.
Signed-off-by: Tao Zhou <tao.zhou1@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>