msm: camera: csiphy: Reset device count on shutdown

When the userspace crashes, as part of the driver clean up
we need to reset the count of number of csiphy devices that
were started so that when camera is opened again it is in
the right state to function.

Change-Id: I540a23afa4c601d98eb50967caf0fe7efa7e6f48
Signed-off-by: Karthik Anantha Ram <kartanan@codeaurora.org>