drm/amd/pm: Correct msg status check for powerlimit

Status 0 indicates success, fix the check before using PPTable limit

Signed-off-by: Lijo Lazar <lijo.lazar@amd.com>
Reviewed-by: Evan Quan <evan.quan@amd.com>
Reviewed-by: Kevin Wang <kevin1.wang@amd.com&gt;`>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>