drm/amd/powerplay: detect version of smu backend (v2)

Print the backend type.

v2: whitespace fixes (Alex)

Signed-off-by: Prike Liang <Prike.Liang@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>