subsurface: Fix messed up stack order of sub-surface

subsurface: Fix messed up stack order of sub-surface

The stack order of sub-surface sometimes got messed up when re-stacking
main surfaces.

Thinking of the case as an example that placing a surface underneath
another surface that has sub-surfaces, it obviously wasn't enough to
re-arrange sub-surfaces stack order only for E_Client given by restack
callback function.

This patch fixes it by updating stack order not only for given E_Client,
but also for E_Clients neighbored with given E_Client.

Change-Id: I95f11c9998ed4f1729e7ca3583a4f41f5dc4edf8