drm/amd/powerplay: revise the calling chain on sensor reading

Update the calling chain from "amdgpu_smu.c -> ${asic}_ppt.c ->
smu_v11/12_0.c -> amdgpu_smu.c (smu_common_read_sensor())" to "
"amdgpu_smu.c -> ${asic}_ppt.c -> smu_v11/12_0.c". This can help
to maintain clear code layers. More similar changes will be coming.

Signed-off-by: Evan Quan <evan.quan@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>