talk.c add busy loop to talk_spell

talk spell can lose the remainder of the words on longer sequences

Change-Id: I5f8f0f42d780ea9d1f00d99ff32746be34c27745

apps/talk.c

@@ -776,6 +776,9 @@ static int _talk_spell(const char* spell, size_t len, bool enqueue)
             talk_id(VOICE_PAUSE, true);
         else if (c == '/')
             talk_id(VOICE_CHAR_SLASH, true);
+
+        while (QUEUE_LEVEL == QUEUE_SIZE - 1) /* queue full - busy loop */
+            yield();
     }
     return 0;
 }