Bluetooth: hci_sync: Fix compilation warning

This fixes the following warning:

net/bluetooth/hci_sync.c:5143:5: warning: no previous prototype for
‘hci_le_ext_create_conn_sync’ [-Wmissing-prototypes]
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

net/bluetooth/hci_sync.c

@@ -5140,8 +5140,8 @@ static void set_ext_conn_params(struct hci_conn *conn,
 	p->max_ce_len = cpu_to_le16(0x0000);
 }
 
-int hci_le_ext_create_conn_sync(struct hci_dev *hdev, struct hci_conn *conn,
-				u8 own_addr_type)
+static int hci_le_ext_create_conn_sync(struct hci_dev *hdev,
+				       struct hci_conn *conn, u8 own_addr_type)
 {
 	struct hci_cp_le_ext_create_conn *cp;
 	struct hci_cp_le_ext_conn_param *p;