fdtdec: only create phandle if caller wants it in fdtdec_add_reserved_memory()

The phandlep pointer returning the phandle to the caller is optional
and if it is not set when calling fdtdec_add_reserved_memory() it is
highly likely that the caller is not interested in a phandle to the
created reserved-memory area and really just wants that area added.

So just don't create a phandle in that case.

Signed-off-by: Heiko Stuebner <heiko.stuebner@theobroma-systems.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
diff --git a/lib/fdtdec.c b/lib/fdtdec.c
index 38a0cff..61af347 100644
--- a/lib/fdtdec.c
+++ b/lib/fdtdec.c
@@ -1339,13 +1339,15 @@
 	if (node < 0)
 		return node;
 
-	err = fdt_generate_phandle(blob, &phandle);
-	if (err < 0)
-		return err;
+	if (phandlep) {
+		err = fdt_generate_phandle(blob, &phandle);
+		if (err < 0)
+			return err;
 
-	err = fdtdec_set_phandle(blob, node, phandle);
-	if (err < 0)
-		return err;
+		err = fdtdec_set_phandle(blob, node, phandle);
+		if (err < 0)
+			return err;
+	}
 
 	/* store one or two address cells */
 	if (na > 1)