[FAB-11040] Fix typo in clean-tests target

This change fixes the clean-tests Makefile target. It was missing the
's'.

Change-Id: Ic3631df0a2260dfcf7acf783414e9e2b23227574
Signed-off-by: Troy Ronda <troy@troyronda.com>

Author: troyronda

Makefile

@@ -481,4 +481,4 @@ clean-temp:
 	-rm -f integration-report.xml report.xml
 
 .PHONY: clean-tests
-clean-test: clean-temp clean-fixtures
+clean-tests: clean-temp clean-fixtures