Bluetooth: Add clarifying comment to l2cap_conn_ready()

There is an extra call to smp_conn_security() for outgoing LE
connections from l2cap_conn_ready() but the reason for this call is far
from clear. After a bit of commit history research and using git blame I
found out that this extra call is for socket-less pairing processes
added by commit 160dc6ac. This patch adds a clarifying comment to the
code for this.
Signed-off-by: Johan Hedberg <johan.hedberg@intel.com>
Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Gustavo Padovan <gustavo.padovan@collabora.co.uk>

net/bluetooth/l2cap_core.c

@@ -1387,6 +1387,9 @@ static void l2cap_conn_ready(struct l2cap_conn *conn)
 	if (!hcon->out && hcon->type == LE_LINK)
 		l2cap_le_conn_ready(conn);
 
+	/* For outgoing pairing which doesn't necessarily have an
+	 * associated socket (e.g. mgmt_pair_device).
+	 */
 	if (hcon->out && hcon->type == LE_LINK)
 		smp_conn_security(hcon, hcon->pending_sec_level);