msm: camera: hfi: Avoid use after free

Use after free of hfi data structure can happen if firmware
is still processing commands while camera close is triggered from
user space. Hence, use global mutexes to synchronize
initialization, tear down and command/message processing.

Change-Id: I69a5f4ab18946b599888d6fb67a7fb174a38698a
Signed-off-by: Lakshmi Narayana Kalavala <lkalaval@codeaurora.org>