drm/amd/pp: Add a new pp feature mask bit for OD feature

when this bit was set on module load,
driver will allow the user over/under gpu
clock and voltage through sysfs.

by default, this bit was not set.

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>