Bluetooth: Classic: add mode change notification for sniff mode

Implement mode change event handling and callback notification for
BR/EDR power mode transitions. Adds br_mode_changed callback to
notify applications when connection switches between active and
sniff modes. Handles HCI mode change events and propagates mode
and interval information to registered callbacks.

Signed-off-by: Kai Cheng <chengkai@xiaomi.com>
6 files changed