hothd: Fix message_usb_unittest asan failure

Hitting the following errors when unit tests are invoked with
meson test -C build --print-errorlogs --logbase testlog-ubasan

```
stderr:
../test/message_usb_unittest.cpp:45:11: runtime error: null pointer passed as argument 2, which is declared to never be null
```
Tested:
root@dedb1f56f871:/opt/bmc/onboarding/changes/hothd# meson test -C build --print-errorlogs --logbase testlog-ubasan
ninja: Entering directory `/opt/bmc/onboarding/changes/hothd/build'
[2/2] Linking target test/message_usb_unittest
 1/16 message_file_unittest                 OK              0.15s
 2/16 message_reinit_unittest               OK              0.14s
 3/16 mtd_util_unittest                     OK              0.14s
 4/16 firmware_mtd_updater_unittest         OK              0.16s
 5/16 firmware_spi_updater_unittest         OK              0.15s
 6/16 message_util_unittest                 OK              0.14s
 7/16 payload_update_unittest               OK              0.13s
 8/16 ec_util_unittest                      OK              0.13s
 9/16 log_collector_util_test               OK              0.12s
10/16 payload_update_cli_test               OK              0.02s
11/16 payload_update_parser_test            OK              0.04s
12/16 hoth_state_unittest                   OK              0.14s
13/16 message_usb_unittest                  OK              0.15s
14/16 hoth_updater_cli_test                 OK              2.04s
15/16 hoth_unittest                         OK              2.55s
16/16 host_command_unittest                 OK              6.26s

Ok:                 16
Expected Fail:      0
Fail:               0
Unexpected Pass:    0
Skipped:            0
Timeout:            0

Full log written to /opt/bmc/onboarding/changes/hothd/build/meson-logs/testlog-ubasan.txt

Change-Id: Icaa1fdf60d607ab3ef0d3d10d46b013146d5a4eb
Signed-off-by: David Tang <davtang@google.com>
1 file changed