[nrf fromtree] bluetooth: att: Fix L2CAP channel section order

The L2CAP channel section is sorted lexicographically. Make sure
that ATT fixed channel will be placed as the last one to ensure
that SMP channel is properly initialized before bt_att_connected
tries to send security request.

Fixes #45820

Signed-off-by: Marek Pieta <[email protected]>
(cherry picked from commit 903672c)

Author: MarekPieta

subsys/bluetooth/host/att.c

@@ -3085,7 +3085,11 @@ static int bt_att_accept(struct bt_conn *conn, struct bt_l2cap_chan **ch)
 	return 0;
 }
 
-BT_L2CAP_CHANNEL_DEFINE(att_fixed_chan, BT_L2CAP_CID_ATT, bt_att_accept, NULL);
+/* The L2CAP channel section is sorted lexicographically. Make sure that ATT fixed channel will be
+ * placed as the last one to ensure that SMP channel is properly initialized before bt_att_connected
+ * tries to send security request.
+ */
+BT_L2CAP_CHANNEL_DEFINE(z_att_fixed_chan, BT_L2CAP_CID_ATT, bt_att_accept, NULL);
 
 #if defined(CONFIG_BT_EATT)
 static k_timeout_t credit_based_connection_delay(struct bt_conn *conn)