sw: remove unused flags field from event/message

It's not even a documented field for WRTD messages.

Spotted during migration to gcc11.2 riscv cross compiler because in some
cases we were not initialising the flags field.

software/firmware/include/wrtd-rt-common.h

@@ -381,7 +381,6 @@ static inline void zero_event(struct wrtd_event *ev)
         zero_id(&ev->id);
 
         ev->seq = 0;
-        ev->flags = 0;
 }
 
 static inline void copy_tstamp(struct wrtd_tstamp *dest,
@@ -399,7 +398,6 @@ static inline void copy_event(struct wrtd_event *dest,
         copy_tstamp(&dest->ts, &src->ts);
         copy_id(&dest->id, &src->id);
         dest->seq = src->seq;
-        dest->flags = src->flags;
 }
 
 /* Returns true iff L is the same id as R.  */
@@ -513,7 +511,7 @@ static int wrtd_send_network(struct wrtd_event *ev)
         msg->ts_ns = ev->ts.ns;
         msg->ts_frac = ev->ts.frac >> 16;
         msg->ts_hi_sec = 0;
-        msg->flags = 0;
+        msg->reserved = 0;
         msg->zero[0] = 0;
         msg->zero[1] = 0;
         msg->pad[0] = 0;
@@ -736,8 +734,6 @@ static void wrtd_recv_network(void)
 
         copy_id(&ev.id, (union wrtd_id*)&msg->event_id);
 
-        ev.flags = msg->flags;
-
         mq_discard(TRTL_RMQ, WRTD_RMQ);
 
         wrtd_log(WRTD_LOG_MSG_EV_NETWORK, WRTD_LOG_NETWORK_RX, &ev, NULL);

software/include/wrtd-common.h

@@ -55,9 +55,6 @@ struct wrtd_event {
 
         /** Sequence number.  */
         uint32_t seq;
-
-        /** Associated flags.  */
-        unsigned char flags;
 };
 
 inline static unsigned char wrtd_id_hash(union wrtd_id *id)
@@ -149,7 +146,7 @@ struct wrtd_message {
         uint32_t ts_ns;
         uint16_t ts_frac;
         uint16_t ts_hi_sec;
-        uint8_t flags;
+        uint8_t reserved;
         uint8_t zero[2];
         uint8_t pad[1];
 };