For MCL, vdev manager resp timer callback should be called in scheduler
context. Hence vdev manager response timer callback code is refactored.
To handle vdev response timer, MCL specific change is to post message to
scheduler thread and handle timer callback in scheduler thread. This MCL
specific change is protected using "SERIALIZE_VDEV_RESP_TIMER" macro.
Change-Id: I4c5a24cd4c8afba92e407fc229a9d2c295cecb57
CRs-Fixed: 2507577