msm: camera: core: Cleanup the logic for shutdown

Before calling release, we need to check the state to avoid
unnecessary release and putref, which would lead to underflow
of refcnt. Also, this change will set the dev and link handles
to non-zero so that the release is complete.

Change-Id: Idffab593dff16288f37b52ba2b98ff9c03df0386
Signed-off-by: Harsh Shah <harshs@codeaurora.org>