drm/amdgpu: skip load smu and sdma microcode on sriov for SIENNA_CICHLID

skip load smu and sdma fw on sriov due to sos,
ta and asd fw have been skipped for SIENNA_CICHLID.

V2:
    move asic check into smu11

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