drm/amdgpu/discovery: add smu13 support for MP1 13.0.7

Enable System Management Unit support.

Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Flora Cui <flora.cui@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>