binman: Replace FILENAME_ALIGN 16 with ATTRIBUTE_ALIGN 4

cbfsutil changed to 4-byte alignment for filenames instead of 16.
Adjust the binman implementation to do the same.

This mirrors commit 5779ca718c in coreboot.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/binman/ftest.py b/tools/binman/ftest.py
index 2875194..5ace2a8 100644
--- a/tools/binman/ftest.py
+++ b/tools/binman/ftest.py
@@ -2667,12 +2667,12 @@
             'cbfs:offset': 0,
             'cbfs:size': len(data),
             'cbfs:image-pos': 0,
-            'cbfs/u-boot:offset': 0x38,
+            'cbfs/u-boot:offset': 0x30,
             'cbfs/u-boot:uncomp-size': len(U_BOOT_DATA),
-            'cbfs/u-boot:image-pos': 0x38,
-            'cbfs/u-boot-dtb:offset': 0xa8,
+            'cbfs/u-boot:image-pos': 0x30,
+            'cbfs/u-boot-dtb:offset': 0xa4,
             'cbfs/u-boot-dtb:size': len(U_BOOT_DATA),
-            'cbfs/u-boot-dtb:image-pos': 0xa8,
+            'cbfs/u-boot-dtb:image-pos': 0xa4,
             }, props)
 
     def testCbfsBadType(self):
@@ -2854,7 +2854,7 @@
 '  u-boot                  0     4  u-boot             0',
 '  section               100   %x  section          100' % section_size,
 '    cbfs                100   400  cbfs               0',
-'      u-boot            128     4  u-boot            28',
+'      u-boot            120     4  u-boot            20',
 '      u-boot-dtb        180   105  u-boot-dtb        80          3c9',
 '    u-boot-dtb          500   %x  u-boot-dtb       400          3c9' % fdt_size,
 '  fdtmap                %x   3bd  fdtmap           %x' %