Bluetooth: Host: Add SCO connection management

Currently, SCO connections and disconnections
are agnostic to upper-layer.

Add two functions, bt_sco_connected and
bt_sco_disconnected, to notify the SCO
connect changes.

For Central side, pass "struct bt_sco_chan"
object when calling bt_conn_create_sco. it
uses to manage the SCO channel for upper-
layer.

For Peripheral side, two functions
bt_sco_server_register and
bt_sco_server_unregister are added to monitor
SCO connection request for upper-layer. The
upper-layer could accept or reject SCO connect
When the connection request received. If the
connect is accepted, the "struct bt_sco_chan"
object could be passed by "sco_server->accept".

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