Move PDK selection into config.mk

config.mk needs to know TARGET_BUILD_PDK in order to select prebuilt
tools.  Move the selection of TARGET_BUILD_PDK into config.mk.

Change-Id: I1f73c92917887f27259b2db64b3779a2fe0df162
diff --git a/core/dumpvar.mk b/core/dumpvar.mk
index c7fb8db..797fdce 100644
--- a/core/dumpvar.mk
+++ b/core/dumpvar.mk
@@ -84,5 +84,10 @@
 $(info   HOST_BUILD_TYPE=$(HOST_BUILD_TYPE))
 $(info   BUILD_ID=$(BUILD_ID))
 $(info   OUT_DIR=$(OUT_DIR))
+ifeq ($(TARGET_BUILD_PDK),true)
+$(info   TARGET_BUILD_PDK=$(TARGET_BUILD_PDK))
+$(info   PDK_FUSION_PLATFORM_ZIP=$(PDK_FUSION_PLATFORM_ZIP))
+endif
+
 $(info ============================================)
 endif