camera2: fix various BpCameraDeviceUser methods to return correct result.

- submitRequest*(): res is the request ID and not always equals to NO_ERROR.
- cancelRequest() and flush(): the result of reading last frame number should be put in resFrameNumber, not in res.

Change-Id: Ic81c58f4ac14c05b3db4bdc5c99f48d00665d3fc
Signed-off-by: John Lin <jolin@mozilla.com>