hw/nvram/fw_cfg: Skip FW_CFG_DATA_GENERATOR when no data to generate

Allow the FW_CFG_DATA_GENERATOR interface get_data() handler to
return NULL when there is nothing to generate. In that case
fw_cfg_add_file_from_generator() will not add any item and
return %true.

Reported-by: Daniel P. Berrangé <berrange@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-Id: <20241213133352.10915-4-philmd@linaro.org>
2 files changed