msm: camera: req_mgr: Populate dev_hdl to notify events to RT devices

When sending a specific request to a particular connected device fails,
we need to notify other devices for which the same request was already
sent. While doing this notification dev_hdl needs to be populated
correctly.

Change-Id: Ib04e600ee96689fa70e471864b6ea14244768007
Signed-off-by: Karthik Anantha Ram <kartanan@codeaurora.org>