Add assets from all density to the SDK system image.

Change-Id: I57500a81607edf04337f0a0a75077c00d6d17274
diff --git a/target/product/sdk.mk b/target/product/sdk.mk
index 25cb236..210bd9c 100644
--- a/target/product/sdk.mk
+++ b/target/product/sdk.mk
@@ -38,6 +38,9 @@
 PRODUCT_NAME := sdk
 PRODUCT_DEVICE := generic
 PRODUCT_LOCALES := \
+	ldpi \
+	hdpi \
+	mdpi \
 	en_US \
 	en_GB \
 	en_CA \