Bluetooth: BR: Improve bt_conn_set_bondable

In current, the bondable flag cannot be configured for each specific
BR connection.
But for LE conn, there is a function `bt_conn_set_bondable` for this
purpose.

Improve `bt_conn_set_bondable` to support BR conn.

Signed-off-by: Lyle Zhu <lyle.zhu@nxp.com>

Author: lylezhu2012

subsys/bluetooth/host/classic/br.c

@@ -240,6 +240,8 @@ void bt_hci_conn_complete(struct net_buf *buf)
 
 	bt_conn_set_state(conn, BT_CONN_CONNECTED);
 
+	atomic_set_bit_to(conn->flags, BT_CONN_BR_BONDABLE, bt_get_bondable());
+
 	bt_conn_connected(conn);
 
 	bt_conn_unref(conn);

subsys/bluetooth/host/classic/ssp.c

@@ -693,7 +693,7 @@ void bt_hci_io_capa_req(struct net_buf *buf)
 		auth = ssp_get_auth(conn);
 	}
 
-	if (!bt_get_bondable()) {
+	if (!atomic_test_bit(conn->flags, BT_CONN_BR_BONDABLE)) {
 		/* If bondable is false, clear bonding flag. */
 		auth = BT_HCI_SET_NO_BONDING(auth);
 	}

subsys/bluetooth/host/conn_internal.h

@@ -57,6 +57,7 @@ enum {
 	 */
 	BT_CONN_AUTO_CONNECT,
 	BT_CONN_BR_LEGACY_SECURE,             /* 16 digits legacy PIN tracker */
+	BT_CONN_BR_BONDABLE,                  /* BR connection is bondable */
 	BT_CONN_USER,                         /* user I/O when pairing */
 	BT_CONN_BR_PAIRING,                   /* BR connection in pairing context */
 	BT_CONN_BR_PAIRED,                    /* BR connection pairing is done */

subsys/bluetooth/host/smp.c

@@ -5447,6 +5447,16 @@ int bt_conn_set_bondable(struct bt_conn *conn, bool enable)
 {
 	struct bt_smp *smp;
 
+	if (IS_ENABLED(CONFIG_BT_CLASSIC) && (conn->type == BT_CONN_TYPE_BR)) {
+		if (enable && atomic_test_and_set_bit(conn->flags, BT_CONN_BR_BONDABLE)) {
+			return -EALREADY;
+		}
+		if (!enable && !atomic_test_and_clear_bit(conn->flags, BT_CONN_BR_BONDABLE)) {
+			return -EALREADY;
+		}
+		return 0;
+	}
+
 	smp = smp_chan_get(conn);
 	if (!smp) {
 		return -EINVAL;