usb: dwc3: gadget: Move vbus draw to workqueue context

In the Linux kernel, the following vulnerability has been resolved: usb: dwc3: gadget: Move vbus draw to workqueue context Currently dwc3_gadget_vbus_draw() can be called from atomic context, which in turn invokes power-supply-core APIs. And some these PMIC APIs have operations that may sleep, leading to kernel panic. Fix this by moving the vbus_draw into a workqueue context.