mctp: Add retry for one-time peer property queries on timeout

The function `query_peer_properties()` is called once during peer initialization
to query basic information after the EID becomes routable.
To improve reliability, this change adds a retry mechanism when the query
fails with `-ETIMEDOUT`. Since these queries are one-time initialization steps,
a single successful attempt is sufficient, and retrying enhances stability
under transient MCTP bus contention or multi-master timing issues.

Testing:
```
root@bmc:~# journalctl -xeu mctpd.service | grep Retrying
Oct 29 00:35:21 bmc mctpd[31801]: mctpd: Retrying to get endpoint types for peer eid 10 net 1 phys physaddr if 4 hw len 1 0x20 state 1. Attempt 1
Oct 29 00:39:00 bmc mctpd[32065]: mctpd: Retrying to get endpoint types for peer eid 10 net 1 phys physaddr if 4 hw len 1 0x20 state 1. Attempt 1
Oct 29 00:39:01 bmc mctpd[32065]: mctpd: Retrying to get endpoint types for peer eid 10 net 1 phys physaddr if 4 hw len 1 0x20 state 1. Attempt 2
Oct 29 00:45:08 bmc mctpd[32360]: mctpd: Retrying to get endpoint types for peer eid 10 net 1 phys physaddr if 4 hw len 1 0x20 state 1. Attempt 1
```

Signed-off-by: Daniel Hsu <[email protected]>

Author: JunYe1993

src/mctpd.c

@@ -2836,21 +2836,42 @@ static int method_learn_endpoint(sd_bus_message *call, void *data,
 static int query_peer_properties(struct peer *peer)
 {
 	int rc;
+	const int max_retries = 4;
 
 	rc = query_get_peer_msgtypes(peer);
 	if (rc < 0) {
 		// Warn here, it's a mandatory command code.
 		// It might be too noisy if some devices don't implement it.
 		warnx("Error getting endpoint types for %s. Ignoring error %d %s",
-		      peer_tostr(peer), rc, strerror(-rc));
+			peer_tostr(peer), rc, strerror(-rc));
+		if (rc == -ETIMEDOUT) {
+			for (int i = 0; i < max_retries; i++) {
+				if (peer->ctx->verbose)
+					warnx("Retrying to get endpoint types for %s. Attempt %d",
+						peer_tostr(peer), i + 1);
+				rc = query_get_peer_msgtypes(peer);
+				if (rc == 0)
+					break;
+			}
+		}
 		rc = 0;
 	}
 
 	rc = query_get_peer_uuid(peer);
 	if (rc < 0) {
 		if (peer->ctx->verbose)
 			warnx("Error getting UUID for %s. Ignoring error %d %s",
-			      peer_tostr(peer), rc, strerror(-rc));
+				peer_tostr(peer), rc, strerror(-rc));
+		if (rc == -ETIMEDOUT) {
+			for (int i = 0; i < max_retries; i++) {
+				if (peer->ctx->verbose)
+					warnx("Retrying to get peer UUID for %s. Attempt %d",
+						peer_tostr(peer), i + 1);
+				rc = query_get_peer_uuid(peer);
+				if (rc == 0)
+					break;
+			}
+		}
 		rc = 0;
 	}