soc: qcom: glink: Fix race condition between channel close & open

Add a new flag to avoid race condition between channel close & open
operations, so that the open operation does not try to use the channel
context that is pending to be deleted.

Change-Id: Ia0c2af4860e53a8a4990090097b2916eec6c8ee2
Signed-off-by: Atish Kumar Patra <apatra@codeaurora.org>
Signed-off-by: Karthikeyan Ramasubramanian <kramasub@codeaurora.org>