msm_fb: wfd: power off overlay 2 block on overlay2 done

Need to call mdp_pipe_ctrl with overlay 2 block off on overlay2
done otherwise the clocks will never go off on suspend.

CRs-Fixed: 431720
Change-Id: I6ae9a7ea9754473aef52443ce352e8f114d767eb
Signed-off-by: Ajay Singh Parmar <aparmar@codeaurora.org>