binman: Support updating the device tree with calc'd info

It is useful to write the position and size of each entry back to the
device tree so that U-Boot can access this at runtime. Add a feature to
support this, along with associated tests.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/binman/test/61_fdt_update_bad.dts b/tools/binman/test/61_fdt_update_bad.dts
new file mode 100644
index 0000000..e5abf31
--- /dev/null
+++ b/tools/binman/test/61_fdt_update_bad.dts
@@ -0,0 +1,32 @@
+// SPDX-License-Identifier: GPL-2.0+
+/dts-v1/;
+
+/ {
+	#address-cells = <1>;
+	#size-cells = <1>;
+
+	binman {
+		pad-byte = <0x26>;
+		size = <0x28>;
+		section@0 {
+			read-only;
+			name-prefix = "ro-";
+			size = <0x10>;
+			pad-byte = <0x21>;
+
+			u-boot {
+			};
+		};
+		section@1 {
+			name-prefix = "rw-";
+			size = <0x10>;
+			pad-byte = <0x61>;
+
+			u-boot {
+			};
+		};
+		_testing {
+			never-complete-process-fdt;
+		};
+	};
+};