nrf5x: refactor device control transfer.

- make control transfer as part of usbd. Class driver must use
usbd_control_ API() instead of dcd_ api.
- change the signature of class driver's control_request
- allow control request complete to stall in staus stage
- move control request parser & handling to usbd.

src/common/tusb_types.h

@@ -203,12 +203,14 @@ typedef enum
   TUSB_EVENT_XFER_STALLED,
 }tusb_event_t;
 
-enum {
+enum
+{
   DESC_OFFSET_LEN  = 0,
   DESC_OFFSET_TYPE = 1
 };
 
-enum {
+enum
+{
   INTERFACE_INVALID_NUMBER = 0xff
 };