test: Update fdt_overlay to do init from tests

Rather than having an init function and then running the tests, create a
test-init function to do it. This will allow us to get rid of the
command function.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/include/test/fdt_overlay.h b/include/test/fdt_overlay.h
index 34e8020..251ad0e 100644
--- a/include/test/fdt_overlay.h
+++ b/include/test/fdt_overlay.h
@@ -12,4 +12,8 @@
 /* Declare a new FDT-overlay test */
 #define FDT_OVERLAY_TEST(_name, _flags)	UNIT_TEST(_name, _flags, fdt_overlay)
 
+/* Declare init for FDT-overlay test */
+#define FDT_OVERLAY_TEST_INIT(_name, _flags)		\
+	UNIT_TEST_INIT(_name, _flags, fdt_overlay)
+
 #endif /* __TEST_OVERLAY_H__ */