add some printf when a class is mounted

add initial tests for rndis

demos/host/src/cdc_serial_app.c

@@ -61,6 +61,9 @@ static uint8_t buffer_in[64] TUSB_CFG_ATTR_USBRAM;
 void tusbh_cdc_mounted_cb(uint8_t dev_addr)
 {
   // application set-up
+
+  printf("a CDC device is mounted\n");
+
   osal_queue_flush(queue_hdl);
   tusbh_cdc_receive(dev_addr, buffer_in, sizeof(buffer_in), true); // first report
 }

demos/host/src/keyboard_app.c

@@ -70,6 +70,9 @@ static inline void process_kbd_report(tusb_keyboard_report_t const * report);
 void tusbh_hid_keyboard_mounted_cb(uint8_t dev_addr)
 {
   // application set-up
+
+  printf("a keyboard device is mounted\n");
+
   osal_queue_flush(queue_kbd_hdl);
   tusbh_hid_keyboard_get_report(dev_addr, (uint8_t*) &usb_keyboard_report); // first report
 }

demos/host/src/mouse_app.c

@@ -70,6 +70,9 @@ static inline void process_mouse_report(tusb_mouse_report_t const * p_report);
 void tusbh_hid_mouse_mounted_cb(uint8_t dev_addr)
 {
   // application set-up
+
+  printf("a mouse device is mounted\n");
+
   osal_queue_flush(queue_mouse_hdl);
   tusbh_hid_mouse_get_report(dev_addr, (uint8_t*) &usb_mouse_report); // first report
 }