drm/amd/powerplay: fix Smatch static checker warnings

1. return -1 instead of -ENOMEM
2. The struct type mismatch warnings.

Signed-off-by: Rex Zhu <Rex.Zhu@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Ken Wang  <Qingqing.Wang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
8 files changed