usb: dwc3: gadget: Synchronize IRQ between soft connect/disconnect

usb: dwc3: gadget: Synchronize IRQ between soft connect/disconnect

[ Upstream commit 9711c67de7482c81e1daca3548fbc5c9603600e3 ]

Ensure that there are no pending events being handled in between soft
connect/disconnect transitions.  As we are keeping interrupts enabled,
and EP0 events are still being serviced, this avoids any stale events from
being serviced.

Reviewed-by: Thinh Nguyen <Thinh.Nguyen@synopsys.com>
Signed-off-by: Wesley Cheng <quic_wcheng@quicinc.com>
Link: https://lore.kernel.org/r/20220817182359.13550-4-quic_wcheng@quicinc.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Stable-dep-of: c8540870af4c ("usb: dwc3: gadget: Improve dwc3_gadget_suspend() and dwc3_gadget_resume()")
Signed-off-by: Sasha Levin <sashal@kernel.org>