usb: dwc3: gadget: Improve dwc3_gadget_suspend() and dwc3_gadget_resume()

Prevent -ETIMEDOUT error on .suspend().
e.g. If gadget driver is loaded and we are connected to a USB host,
all transfers must be stopped before stopping the controller else
we will not get a clean stop i.e. dwc3_gadget_run_stop() will take
several seconds to complete and will return -ETIMEDOUT.

Handle error cases properly in dwc3_gadget_suspend().
Simplify dwc3_gadget_resume() by using the introduced helper function.

Fixes: 9f8a67b6

 ("usb: dwc3: gadget: fix gadget suspend/resume")
Cc: stable@vger.kernel.org
Suggested-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Signed-off-by: Roger Quadros <rogerq@kernel.org>
Acked-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Link: https://lore.kernel.org/r/20230503110048.30617-1-rogerq@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>