usb: dwc3: run gadget disconnect from sleepable suspend context

In the Linux kernel, the following vulnerability has been resolved: usb: dwc3: run gadget disconnect from sleepable suspend context dwc3_gadget_suspend() takes dwc->lock with IRQs disabled and then calls dwc3_disconnect_gadget(). For async callbacks that helper only uses plain spin_unlock()/spin_lock(), so the gadget ->disconnect() callback still runs with IRQs disabled and any sleepable callback trips Lockdep. This issue was found by our static analysis tool and then manually reviewed against the current tree. The grounded PoC kept the dwc3_gadget_suspend() -> dwc3_disconnect_gadget() -> gadget_driver->disconnect() chain, and Lockdep reported: BUG: sleeping function called from invalid context gadget_disconnect+0x21/0x39 [vuln_msv] dwc3_gadget_suspend.constprop.0+0x2b/0x42 [vuln_msv] Keep the disconnect callback selection in one common helper, but add a sleepable suspend-side wrapper which snapshots the callback under dwc->lock and then runs it after spin_unlock_irqrestore(). The regular event path still uses the existing spin_unlock()/spin_lock() window.