Remove unused property.

Change-Id: I14cfccf104881fdbca2b926e289b90e4bfad1c32
diff --git a/target/product/full_base.mk b/target/product/full_base.mk
index 9b1a826..aec3537 100644
--- a/target/product/full_base.mk
+++ b/target/product/full_base.mk
@@ -40,7 +40,6 @@
 
 # Additional settings used in all AOSP builds
 PRODUCT_PROPERTY_OVERRIDES := \
-    ro.com.android.dateformat=MM-dd-yyyy \
     ro.config.ringtone=Ring_Synth_04.ogg \
     ro.config.notification_sound=pixiedust.ogg