binman: Add an entry for a Chromium vblock

This adds support for a Chromium verified boot block, used to sign a
read-write section of the image.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/binman/test/75_vblock_no_content.dts b/tools/binman/test/75_vblock_no_content.dts
new file mode 100644
index 0000000..676d947
--- /dev/null
+++ b/tools/binman/test/75_vblock_no_content.dts
@@ -0,0 +1,23 @@
+// SPDX-License-Identifier: GPL-2.0+
+/dts-v1/;
+
+/ {
+	#address-cells = <1>;
+	#size-cells = <1>;
+
+	binman {
+		u_boot: u-boot {
+		};
+
+		vblock {
+			keyblock = "firmware.keyblock";
+			signprivate = "firmware_data_key.vbprivk";
+			version = <1>;
+			kernelkey = "kernel_subkey.vbpubk";
+			preamble-flags = <1>;
+		};
+
+		dtb: u-boot-dtb {
+		};
+	};
+};