usb_gadget_disconnect — software-controlled disconnect from USB host
int usb_gadget_disconnect (struct usb_gadget * gadget);
Disables the D+ (or potentially D-) pullup, which the host may see as a disconnect (when a VBUS session is active). Not all systems support software pullup controls.
This routine may be used during the gadget driver bind call to prevent
the peripheral from ever being visible to the USB host, unless later
usb_gadget_connect is called. For example, user mode components may
need to be activated before the system can talk to hosts.
Returns zero on success, else negative errno.