bfdd: fix garbage "port" string

bfd_recv_ipv4() is getting an uninitialized buffer passed in as port,
and then checks it without clearing it first.  Thus we can end up
leaving garbage data in it.

Signed-off-by: David Lamparter <equinox@diac24.net>

bfdd/bfd_packet.c

@@ -248,6 +248,8 @@ ssize_t bfd_recv_ipv4(int sd, uint8_t *msgbuf, size_t msgbuflen, uint8_t *ttl,
 	struct iovec iov[1];
 	uint8_t cmsgbuf[255];
 
+	port[0] = '\0';
+
 	/* Prepare the recvmsg params. */
 	iov[0].iov_base = msgbuf;
 	iov[0].iov_len = msgbuflen;