Enabling BBSim based TT tests

Change-Id: I0443c1d58bb5c103e3e54e64ccd36b788a6dfc82
diff --git a/Makefile b/Makefile
index 22e1bf6..1ce9e8c 100755
--- a/Makefile
+++ b/Makefile
@@ -44,8 +44,7 @@
 ROBOT_SCALE_MULT_ONU_FILE       ?= $(ROOT_DIR)/tests/data/bbsim-kind-8x8.yaml
 ROBOT_DEBUG_LOG_OPT             ?=
 ROBOT_MISC_ARGS                 ?=
-# TODO: TT workflow not yet supported on BBSim
-ROBOT_SANITY_TT_SINGLE_PON_FILE    ?=
+ROBOT_SANITY_TT_SINGLE_PON_FILE    ?= $(ROOT_DIR)/tests/data/bbsim-kind-tt.yaml
 
 # for backwards compatibility
 sanity-kind: sanity-single-kind