Bluetooth: Avoid calling undefined smp_conn_security()

Commit ff03261a ('Bluetooth: Fix
sending a HCI Authorization Request over LE links', commit
d8343f12 upstream) added an
call to smp_conn_security() from hci_conn_security().  The
former is only defined if CONFIG_BT_L2CAP=y.

This is not required in mainline since commit
f1e91e16 ('Bluetooth: Always compile
SCO and L2CAP in Bluetooth Core') removed that option.
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

net/bluetooth/hci_conn.c

@@ -642,8 +642,10 @@ int hci_conn_security(struct hci_conn *conn, __u8 sec_level, __u8 auth_type)
 {
 	BT_DBG("conn %p", conn);
 
+#ifdef CONFIG_BT_L2CAP
 	if (conn->type == LE_LINK)
 		return smp_conn_security(conn, sec_level);
+#endif
 
 	/* For sdp we don't need the link key. */
 	if (sec_level == BT_SECURITY_SDP)