usb: gadget: cser: Requeue OUT USB requests if ECONNRESET is received

During enumeration, the host can send a clear feature EP_HALT.  When
the UDC receives this command, it will cancel any pending requests and
return -ECONNRESET to the function driver.  Since the clear EP_HALT
occurs after the cser driver has already submitted the OUT USB reqs,
there is no other method to restart these transfers.  Resubmit OUT
reqs specifically when ECONNRESET is seen.

Change-Id: I925170d389048f84579c9b53128effdbef5c9d6a
Signed-off-by: Wesley Cheng <wcheng@codeaurora.org>