msm: qcn: Synchronize clients operating at different modes

Add synchronization support between clients that operate on different
modes, i.e. synchronous or asynchronous. The synchronous client will
momentarily switch to asynchronous if any asynchronous transmission is
scheduled.

Change-Id: I41aec9bff950d2816a9ce55017e118e8504be77a
Signed-off-by: Amandeep Singh <amansing@codeaurora.org>