VOL-1361 - OpenOLT driver agent build artifacts copied inot voltha container

Excluded entire agent subproject folder from voltha docker container context
while building voltha image.

Change-Id: I6464023bd594d2b0fb9608e6ded42b7f8363a050
diff --git a/.dockerignore b/.dockerignore
index 8d94c00..983c7b5 100644
--- a/.dockerignore
+++ b/.dockerignore
@@ -8,3 +8,7 @@
 
 # npm
 **/node_modules
+
+# OpenOLT driver agent
+voltha/adapters/openolt/core/**/*
+#voltha/adapters/openolt/core