usb: dwc3: gadget: Avoid continuing preparing TRBs during teardown

Add checks similar to dwc3_gadget_ep_queue() before kicking off
transfers after getting an endpoint completion event.   Since cleaning
up completed requests will momentarily unlock dwc->lock, there is a
chance for a sequence like pullup disable to be executed.  This can
lead to preparing a TRB, which will be removed by the pullup disable
routine.

Signed-off-by: Wesley Cheng <wcheng@codeaurora.org>
Link: https://lore.kernel.org/r/1616146285-19149-2-git-send-email-wcheng@codeaurora.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>