drm/amd/pp: Make sure clock_voltage_limit_table on dc is valid

if vbios not set the max clock voltage limit table for DC mode,
Set the table as sama as the table for AC mode.

Reviewed-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>