drm/amd/powerplay: original power state table should not be changed.

power state table was set based on vbios and should not be changed.
when client need to change power state, just make a copy and send to
smu.

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>