Remove PRODUCT_IOT.

Test: treehugger
Change-Id: Ic214ebda6c65e7e51e39151b10f4ce965b35c121
diff --git a/core/config.mk b/core/config.mk
index a6a76cb..55b269d 100644
--- a/core/config.mk
+++ b/core/config.mk
@@ -118,6 +118,7 @@
   ARCH_X86_HAVE_SSE4_2 \
   ARCH_X86_HAVE_SSSE3 \
 )
+$(KATI_obsolete_var PRODUCT_IOT)
 
 # Used to force goals to build.  Only use for conditionally defined goals.
 .PHONY: FORCE