soc: qcom: bam_dmux: Catch invalid remote open operations

Receiving a remote open command for a channel that is already in the remote
open state is invalid and typically signifies a significant issue in the
remote side which should be immediately caught and debugged.

Change-Id: Ic5a42d7d52da36ab0498604d0350136fd9245ab0
Signed-off-by: Jeffrey Hugo <jhugo@codeaurora.org>