Fixes the following sparse warnings:

lib/test_firmware.c:99:20: warning:
 symbol 'test_fw_config' was not declared. Should it be static?
Signed-off-by: NWei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>