msm: camera: req_mgr: Populate sync mode info in request manager

Add support to save incoming sync_mode from schedule_request
into request slots and populate sync mode links of master,
aux into each other. This will be used while handling
request synchronization in dual camera use cases.

Change-Id: I9a9414332ba2c858c45bd24c9e6e2ad29bd843a1
Signed-off-by: Pavan Kumar Chilamkurthi <pchilamk@codeaurora.org>
Signed-off-by: Karthik Anantha Ram <kartanan@codeaurora.org>