audio: Update ISO endpoint attributes

Explicit feedback attribute was missing.
No synchronization now also has definition.

src/class/audio/audio.h

@@ -497,11 +497,13 @@ typedef enum
 /// Isochronous End Point Attributes
 typedef enum
 {
+  TUSB_ISO_EP_ATT_NO_SYNC         = 0x00,
   TUSB_ISO_EP_ATT_ASYNCHRONOUS    = 0x04,
   TUSB_ISO_EP_ATT_ADAPTIVE        = 0x08,
   TUSB_ISO_EP_ATT_SYNCHRONOUS     = 0x0C,
   TUSB_ISO_EP_ATT_DATA            = 0x00, ///< Data End Point
-  TUSB_ISO_EP_ATT_FB              = 0x20, ///< Feedback End Point
+  TUSB_ISO_EP_ATT_EXPLICIT_FB     = 0x10, ///< Feedback End Point
+  TUSB_ISO_EP_ATT_IMPLICIT_FB     = 0x20, ///< Data endpoint that also serves as an implicit feedback
 } tusb_iso_ep_attribute_t;
 
 /// Audio Class-Control Values UAC2