binman: Support alignment of files

When packing files it is sometimes useful to align the start of each file,
e.g. if the flash driver can only access 32-bit-aligned data. Provides a
new property to support this.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/binman/test/084_files.dts b/tools/binman/test/084_files.dts
index 83ddb78..8f09afd 100644
--- a/tools/binman/test/084_files.dts
+++ b/tools/binman/test/084_files.dts
@@ -5,7 +5,7 @@
 	binman {
 		files {
 			pattern = "files/*.dat";
-			compress = "none";
+			files-compress = "none";
 		};
 	};
 };
diff --git a/tools/binman/test/190_files_align.dts b/tools/binman/test/190_files_align.dts
new file mode 100644
index 0000000..213ba96
--- /dev/null
+++ b/tools/binman/test/190_files_align.dts
@@ -0,0 +1,12 @@
+// SPDX-License-Identifier: GPL-2.0+
+/dts-v1/;
+
+/ {
+	binman {
+		files {
+			pattern = "files/*.dat";
+			files-compress = "none";
+			files-align = <4>;
+		};
+	};
+};