soc: qmi: dfc: fix dead loop in workqueue dfc_wq

The dead loop is caused by destroy_workqueue() in the same dfc_wq
context when dfc_svc_init does cleanup on failure.
This fixes the issue by exit on failure and letting the cleanup be
done by client exit call.
The client exit will be called on exit request or SSR.

Change-Id: Ic32f038b390a68faa0c461c8089e50d8906b4b2b
Acked-by: Ning Cai <ncai@qti.qualcomm.com>
Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>