This reverts commit f2dbabe786
.
This change is not needed any more because we are caching the MDP pipe
contents when closing the channel. So no need to wait for postFB finish.
Change-Id: Ia6f01c33953762cb7a97e0b2b795d9afeb60d2d9
(cherry picked from commit 441f1824593bb12a97508b426b597a16b35091e6)