Clean up local imports when building. Issues can occur when version are updated otherwise.

Change-Id: Ide886eb07f788cab0c1d16584243f231819011fe
diff --git a/Makefile b/Makefile
index 63d2f35..f03ff01 100644
--- a/Makefile
+++ b/Makefile
@@ -98,6 +98,7 @@
 ifdef LOCAL_PROTOS
 	mkdir -p vendor/github.com/opencord/voltha-protos/go
 	cp -r ${GOPATH}/src/github.com/opencord/voltha-protos/go/* vendor/github.com/opencord/voltha-protos/go
+	rm -rf python/local_imports/voltha-protos
 	mkdir -p python/local_imports/voltha-protos/dist
 	cp ../voltha-protos/dist/*.tar.gz python/local_imports/voltha-protos/dist/
 endif
@@ -105,6 +106,7 @@
 local-pyvoltha:
 	@mkdir -p python/local_imports
 ifdef LOCAL_PYVOLTHA
+	rm -rf python/local_imports/pyvoltha
 	mkdir -p python/local_imports/pyvoltha/dist
 	cp ../pyvoltha/dist/*.tar.gz python/local_imports/pyvoltha/dist/
 endif