drm/amd/powerplay: add interface to get uclk dpm table

dc needs get uclk dpm table for bandwidth calculation

Signed-off-by: hersen wu <hersenxs.wu@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Reviewed-by: Huang Rui <ray.huang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>