Bluetooth: Fix rejecting SMP security request in slave role

The SMP security request is for a slave role device to request the
master role device to initiate a pairing request. If we receive this
command while we're in the slave role we should reject it appropriately.
Signed-off-by: NJohan Hedberg <johan.hedberg@intel.com>
Signed-off-by: NMarcel Holtmann <marcel@holtmann.org>

net/bluetooth/smp.c

@@ -739,6 +739,9 @@ static u8 smp_cmd_security_req(struct l2cap_conn *conn, struct sk_buff *skb)
 
 	BT_DBG("conn %p", conn);
 
+	if (!(conn->hcon->link_mode & HCI_LM_MASTER))
+		return SMP_CMD_NOTSUPP;
+
 	hcon->pending_sec_level = authreq_to_seclevel(rp->auth_req);
 
 	if (smp_ltk_encrypt(conn, hcon->pending_sec_level))