Fix mbtk_otad for dfota.

Change-Id: I928fba9e76a79c8223685a13b5b053b67496973e
diff --git a/mbtk/mbtk_otad/Makefile b/mbtk/mbtk_otad/Makefile
index 1ddd589..add853e 100755
--- a/mbtk/mbtk_otad/Makefile
+++ b/mbtk/mbtk_otad/Makefile
@@ -13,8 +13,8 @@
 # -Wno-error=unused-function
 CFLAGS +=
 
-# -DCONFIG_AB_SYSTEM_DFOTA
-DEFINE += -DCONFIG_AB_SYSTEM -DCONFIG_AB_SYSTEM_DFOTA
+# -DCONFIG_AB_SYSTEM  -DCONFIG_AB_SYSTEM_DFOTA
+DEFINE +=
 
 MY_FILES_PATH:=$(LOCAL_PATH)/src