libcopybit: update the target config_mask for transformation

With the new C2D optimization, the layer transformation is
passed through the config_mask.  If two layers had same
transform then the transform info was lost, fix that by
updating the config_mask when the layer has transformation info

Change-Id: Idecb5b16a65269fd13eead9a2de27a4756435583
CRs-fixed: 453083