Makefile update

Change-Id: I21a94ec0d2ca5ef457fb025cdef5c82e1c2b73b1
diff --git a/Makefile b/Makefile
index d6286bf..138eea9 100644
--- a/Makefile
+++ b/Makefile
@@ -78,11 +78,8 @@
 	docker build -t cord/chameleon -f Dockerfile.chameleon .
 	docker build -t cord/ofagent -f Dockerfile.ofagent .
 
-docker-base: .docker-base-built
-
-.docker-base-built: Dockerfile.base Makefile requirements.txt
+docker-base:
 	docker build -t cord/voltha-base -f Dockerfile.base .
-	touch .docker-base-built
 
 protos:
 	make -C voltha/protos