added usbd_edpt_xfer/usbd_edpt_busy to replace dcd_edpt_transfer/dcd_edpt_busy()

- improve fifo write/read_n with only one lock
- use usbd_edpt_xfer/usbd_edpt_busy for hid/cdc/msc class driver
- replace cdc read's pending_read_from_host by usbd_edpt_busy()

examples/device/cdc_msc_hid/src/main.c

@@ -201,7 +201,7 @@ void hid_task(void)
       tud_hid_mouse_report(REPORT_ID_MOUSE, 0x00, delta, delta, 0, 0);
 
       // delay a bit before attempt to send keyboard report
-      board_delay(2);
+      board_delay(10);
     }
   }