unit-test: Fix PEP8 E731 violation

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

Change-Id: Ie9bbbfbd6298bef2e1131ba1de72ed5594341c84
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
diff --git a/scripts/unit-test.py b/scripts/unit-test.py
index 9344a83..8224fb3 100755
--- a/scripts/unit-test.py
+++ b/scripts/unit-test.py
@@ -1071,7 +1071,8 @@
                 print arg,
             print
     else:
-        printline = lambda *l: None
+        def printline(*line):
+            pass
 
     CODE_SCAN_DIR = WORKSPACE + "/" + UNIT_TEST_PKG