Fix up the powergating logic.
Signed-off-by: Rex Zhu <Rex.Zhu@amd.com>
Ack-by: Tom St Denis <tom.stdenis@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>