ntpd: Fix segfault when same IP on multiple interfaces

Use the protype socket to obtain the IP address for an error message.
Using the resultant socket address, a NULL because create_interface()
had failed, results in SIGSEGV.

To reproduce this bug,

ifconfig bridge100 create
ifconfig bridge100 10.10.10.10/24
ifconfig bridge101 create
ifconfig bridge101 10.10.10.10/24
ntpd -n

PR:		291119
MFC after:	3 days

contrib/ntp/ntpd/ntp_io.c

@@ -1923,7 +1923,7 @@ update_interfaces(
 
 			msyslog(LOG_ERR,
 				"cannot bind address %s",
-				stoa(&ep->sin));
+				stoa(&ep2->sin));
 		}
 		free(ep2);
 	}