Ignore bng and fabric-tofino sub repos

Change-Id: I912ebfb746fd3f17122295bce6e2b7cb6f06bbbc
diff --git a/.gitignore b/.gitignore
index dcfbea3..f0defa7 100644
--- a/.gitignore
+++ b/.gitignore
@@ -52,4 +52,5 @@
 apps/sadis/
 apps/igmpproxy/
 apps/dhcpl2relay/
-
+apps/fabric-tofino/
+apps/bng/