stm32/usbdev: Fix compile error if MICROPY_HW_USB_CDC_NUM is set to 2.
Fixes regression introduced by
@@ -556,7 +556,6 @@ int USBD_SelectMode(usbd_cdc_msc_hid_state_t *usbd, uint32_t mode, USBD_HID_Mode
n += make_hid_desc_ep(d + n, hid_info, HID_IFACE_NUM_WITH_CDC2_MSC, HID_IN_EP_WITH_CDC2_MSC, HID_OUT_EP_WITH_CDC2_MSC);
usbd->cdc[0]->iface_num = CDC_IFACE_NUM_WITH_MSC;
usbd->cdc[1]->iface_num = CDC2_IFACE_NUM_WITH_MSC;
- usbd->cdc[2]->iface_num = CDC3_IFACE_NUM_WITH_MSC;
usbd->hid->in_ep = HID_IN_EP_WITH_CDC2_MSC;
usbd->hid->out_ep = HID_OUT_EP_WITH_CDC2_MSC;
usbd->hid->iface_num = HID_IFACE_NUM_WITH_CDC2_MSC;
