make test: add checkstyle target

Change-Id: I59d3c3bc77474c96e1d6fa51811c1b13fb9a6c5b
Signed-off-by: Klement Sekera <ksekera@cisco.com>
diff --git a/Makefile b/Makefile
index 12f4048..f1813a3 100644
--- a/Makefile
+++ b/Makefile
@@ -96,6 +96,7 @@
 	@echo " test-wipe-doc       - wipe documentation for test framework"
 	@echo " test-cov            - generate code coverage report for test framework"
 	@echo " test-wipe-cov       - wipe code coverage report for test framework"
+	@echo " test-checkstyle     - check PEP8 compliance for test framework"
 	@echo ""
 	@echo "Make Arguments:"
 	@echo " V=[0|1]             - set build verbosity level"
@@ -239,6 +240,9 @@
 test-wipe-cov:
 	@make -C test wipe-cov
 
+test-checkstyle:
+	@make -C test checkstyle
+
 retest:
 	$(call test,vpp_lite,vpp_lite,retest)