drm/amd/pm: ac/dc change for smu_v13_0

fixed the issue: gpu runs in dc mode but it is expected to be in ac mode.
this causes the lower performance on smu_v13_0

Signed-off-by: Kenneth Feng <kenneth.feng@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>