drm/amd/swsmu: add missing feature map for sienna_cichlid

it will cause smu sysfs node of "pp_features" show error.

Signed-off-by: Kevin Wang <kevin1.wang@amd.com>
Reviewed-by: Likun Gao <Likun.Gao@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>