drm/amdgpu: resolved bug in UMC RAS CE query

switch CE counter register access' to use SMN

disable UMC indexing mode

Reviewed-by: Tao Zhou <tao.zhou1@amd.com>
Signed-off-by: John Clements <john.clements@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>