drm/amd/pp: Export notify_smu_enable_pwe to display

Display can notify smu to enable pwe after gpu suspend.
It is used in case when display resumes from S3 and wants to start
audio driver by enabling pwe

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