trxcon/l1ctl.c: init DL info header in l1ctl_tx_rach_conf()

Since we only set both ARFCN and TDMA frame number of the DL info
header, other fields remain uninitialized. Let's memset() them.

Change-Id: Ib39c333f1724fefa5d8bd8a2315b77a5612f7fa9

src/host/trxcon/l1ctl.c

@@ -244,6 +244,8 @@ int l1ctl_tx_rach_conf(struct l1ctl_link *l1l,
 		return -ENOMEM;
 
 	dl = put_dl_info_hdr(msg, NULL);
+	memset(dl, 0x00, sizeof(*dl));
+
 	dl->band_arfcn = htons(band_arfcn);
 	dl->frame_nr = htonl(fn);