[Why]
SMU firmware has not supported MALL PG.

[How]
Disable MALL PG and make it always on until SMU firmware is ready.
Signed-off-by: Li Ma <li.ma@amd.com>
Reviewed-by: Tim Huang <Tim.Huang@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>