drm/amd/powerplay: add golden dpm table to backup default DPM table (v2)

Backup default DPM table into golden dpm table.

v2: fix dpm_context and golden_dpm_context kfree two times issue.

Signed-off-by: Likun Gao <Likun.Gao@amd.com>
Reviewed-by: Kevin Wang <kevin1.wang@amd.com>
Reviewed-by: Evan Quan <evan.quan@amd.com>
Acked-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>