Previously if starting/stopping BLE advertising when BLE Mesh
is enabled, the corresponding events will be notified through
the callback registered by esp_ble_mesh_register_prov_callback().
With this commit, the func esp_ble_mesh_register_ble_callback()
needs to be invoked for resgitering the callback used for BLE
coexistence related functionalities (i.e. ADV/SCAN).