drm/amdgpu: drop psp ih programming for sriov guest on navi

the psp access ih path is not needed in navi

Signed-off-by: Hawking Zhang <Hawking.Zhang@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Jane Jian <Jane.Jian@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>