binman: Add support for sections

It is useful to be able to split an image into multiple sections,
each with its own size and position, for cases where a flash device has
read-only and read-write portions.

Add support for this.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/binman/test/55_sections.dts b/tools/binman/test/55_sections.dts
new file mode 100644
index 0000000..2ada395
--- /dev/null
+++ b/tools/binman/test/55_sections.dts
@@ -0,0 +1,28 @@
+// SPDX-License-Identifier: GPL-2.0+
+
+/dts-v1/;
+
+/ {
+	#address-cells = <1>;
+	#size-cells = <1>;
+
+	binman {
+		pad-byte = <0x26>;
+		size = <0x28>;
+		section@0 {
+			read-only;
+			size = <0x10>;
+			pad-byte = <0x21>;
+
+			u-boot {
+			};
+		};
+		section@1 {
+			size = <0x10>;
+			pad-byte = <0x61>;
+
+			u-boot {
+			};
+		};
+	};
+};