drm/amd/pm: correct the logics for retreiving SMU13 OD setting limits

To better meet the growing demainds for more OD features.

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