unit-test: Fix PEP8 E731 violation
unit-test: Fix PEP8 E731 violation

E731: do not assign a lambda expression, use a def

Change-Id: Ie9bbbfbd6298bef2e1131ba1de72ed5594341c84
Signed-off-by: Andrew Jeffery <02e0a999c50b1f88df7a8f5a04e1b76b35ea6a88@aj.id.au>

openbmc/openbmc-build-scripts,openbmc/openbmc-build-scripts