omni: move to PRODUCT_SYSTEM_DEFAULT_PROPERTIES

Change-Id: I76c0a4a3b6c4572f1b0197c4fc39151640ef9de1
diff --git a/config/phone-xxhdpi-2048-dalvik-heap.mk b/config/phone-xxhdpi-2048-dalvik-heap.mk
index 9489593..c79c250 100644
--- a/config/phone-xxhdpi-2048-dalvik-heap.mk
+++ b/config/phone-xxhdpi-2048-dalvik-heap.mk
@@ -17,7 +17,7 @@
 # Provides overrides to configure the Dalvik heap for a 2G phone
 # 192m of RAM gives enough space for 5 8 megapixel camera bitmaps in RAM.
 
-PRODUCT_PROPERTY_OVERRIDES += \
+PRODUCT_SYSTEM_DEFAULT_PROPERTIES += \
     dalvik.vm.heapstartsize=16m \
     dalvik.vm.heapgrowthlimit=192m \
     dalvik.vm.heapsize=512m \