usb: dwc3: gadget: Refactor EP0 forced stall/restart into a separate API

Several sequences utilize the same routine for forcing the control endpoint
back into the SETUP phase.  This is required, because those operations need
to ensure that EP0 is back in the default state.

Acked-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Signed-off-by: Wesley Cheng <quic_wcheng@quicinc.com>
Link: https://lore.kernel.org/r/20230420212759.29429-3-quic_wcheng@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>