sdk-addon: Prevent nested data/ inside $(PRIVATE_STAGING_DIR)

Current logic recursively copies $(PRODUCT_OUT)/data into $(PRIVATE_STAGING_DIR)/data
This leads to creating $(PRIVATE_STAGING_DIR)/data/data on incremental
builds causing emulator to fail to boot.

Test: Build emulator sdk_addon twice, extract the zip, run the emulator
and verify it boots and reaches homescreen

Change-Id: I9e74d2ab28f9fbd67362578672d25d438fad0d53
diff --git a/core/tasks/sdk-addon.mk b/core/tasks/sdk-addon.mk
index 7acac72..2fd4ce9 100644
--- a/core/tasks/sdk-addon.mk
+++ b/core/tasks/sdk-addon.mk
@@ -126,7 +126,7 @@
 $(full_target_img): $(full_target) $(addon_img_source_prop) | $(SOONG_ZIP)
 	@echo Packaging SDK Addon System-Image: $@
 	$(hide) mkdir -p $(dir $@)
-	cp -R $(PRODUCT_OUT)/data $(PRIVATE_STAGING_DIR)/data
+	cp -R $(PRODUCT_OUT)/data $(PRIVATE_STAGING_DIR)
 	$(hide) $(SOONG_ZIP) -o $@ -C $(dir $(PRIVATE_STAGING_DIR)) -D $(PRIVATE_STAGING_DIR)