msm: camera: common: Return appropriate error code for cancelled requests

If a request is submitted post flush and the request ID of that
request is <= last flush req ID return an appropriate error code
to indicate the same.

CRs-Fixed: 2720555
Change-Id: Ic26c4fc5f0ba490ed277b3bb301cc02d1fa027d6
Signed-off-by: Karthik Anantha Ram <kartanan@codeaurora.org>
Signed-off-by: Mukund Madhusudan Atre <matre@codeaurora.org>