soc: qcom: glink: Fix race condition for dummy transport deletion

In ssr/unregister_transport scenario, remote disconnect is faked
to all clients and the channels are moved to a dummy transport
to be closed in future. The dummy transport is deleted once all
the channels on it are fully closed. This may lead to a race
condition where the dummy transport can be deleted while some
channels are still being moved to it.

Fix the race condition by first moving the channels to dummy
transport together and fake remote disconnect to the clients
one by one so that dummy transport will be deleted only
after all the channels are closed.

Change-Id: I0a8e78e562594751b2984f4df4d6030c5abb5d41
Signed-off-by: Atish Kumar Patra <apatra@codeaurora.org>