Remove the default sdk.atree if custom one is set.

Change-Id: I5d20b030db5ef29d7ff6eb64a0a1e11a4283e85d
diff --git a/core/Makefile b/core/Makefile
index 6956c22..7089f6d 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -1554,7 +1554,6 @@
 
 sdk_atree_files := \
 	$(atree_dir)/sdk.exclude.atree \
-	$(atree_dir)/sdk.atree \
 	$(atree_dir)/sdk-$(HOST_OS)-$(HOST_ARCH).atree \
 	$(sdk_tools_atree_files)
 
@@ -1583,7 +1582,7 @@
 	$(INSTALLED_SDK_BUILD_PROP_TARGET) \
 	$(INSTALLED_BUILD_PROP_TARGET) \
 	$(ATREE_FILES) \
-	$(atree_dir)/sdk.atree \
+	$(sdk_atree_files) \
 	$(sdk_tools_atree_files) \
 	$(HOST_OUT_EXECUTABLES)/atree \
 	$(HOST_OUT_EXECUTABLES)/line_endings