btc_storage_load_bonded_devices() function

* Function btc_storage_load_bonded_devices * Description BTC storage API - Loads all the bonded devices from NVRAM * and adds to the BTA. * Additionally, this API also invokes the adaper_properties_cb * and remote_device_properties_cb for each of the bonded devices. * Returns BT_STATUS_SUCCESS if successful, BT_STATUS_FAIL otherwise