Move pdk fusion platform.zip file under vendor/pdk

Look for the platform.zip file in:
vendor/pdk/DEVICE/PRODUCT-BUILD_VARIANT/platform/platform.zip

Change-Id: I275029842fdf13867d5141549ca8c39abb23600b
diff --git a/core/pdk_config.mk b/core/pdk_config.mk
index 98f34a5..729a44a 100644
--- a/core/pdk_config.mk
+++ b/core/pdk_config.mk
@@ -17,7 +17,7 @@
 # 2) TARGET_BUILD_PDK is passed in from the environment
 
 # TODO: what's the best default location?
-_pdk_fusion_default_platform_zip := $(OUT_DIR)/platform.zip
+_pdk_fusion_default_platform_zip := vendor/pdk/$(TARGET_DEVICE)/$(TARGET_PRODUCT)-$(TARGET_BUILD_VARIANT)/platform/platform.zip
 ifneq (,$(wildcard $(_pdk_fusion_default_platform_zip)))
 $(info $(_pdk_fusion_default_platform_zip) found, do a PDK fusion build.)
 PDK_FUSION_PLATFORM_ZIP := $(_pdk_fusion_default_platform_zip)