msm: ipc: Cleanup unused elements

Some of the mutexes, lists and wait queues are just initialized and left
unused in IPC Router. Cleanup those unused variables/elements.

Change-Id: Ifa363afd4315f8c24eb47c74fd44ac02d0b77eff
Signed-off-by: Karthikeyan Ramasubramanian <kramasub@codeaurora.org>