drm/amd/powerplay: enable DiDt feature for polaris10/11.

DIDT is a power saving feature which helps limit power
consumption in order to hit a target power allocation.

v1: delete temp file added accidentally.

Signed-off-by: Rex Zhu <Rex.Zhu@amd.com>
Reviewed-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>