Adjust the serverbufferintegrations to use bind texture api

It mapps closer to the underlying OpenGL architecture

Change-Id: I4e0dca4d54670846488c86df2a0fa0c58d49734d
Reviewed-by: Jan Arne Petersen <jan.petersen@kdab.com>
Reviewed-by: Laszlo Agocs <laszlo.agocs@digia.com>