drm/amdgpu/pm: wire up hwmon fan speed for smu 14.0.2

Add callbacks for fan speed fetching.

Closes: drm/amd#4034


Reviewed-by: Kenneth Feng <kenneth.feng@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 90df6db6)
Cc: stable@vger.kernel.org # 6.12.x