util/cbfstool: Add optional argument ibb

* Mark files in CBFS as IBB (Initial BootBlock)
* Will be used to identify the IBB by any TEE

Change-Id: Idb4857c894b9ee1edc464c0a1216cdda29937bbd
Signed-off-by: Philipp Deppenwiese <zaolin.daisuki@gmail.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/29744
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>

src/commonlib/include/commonlib/cbfs_serialized.h

@@ -157,6 +157,7 @@ struct cbfs_file_attribute {
 #define CBFS_FILE_ATTR_TAG_HASH 0x68736148
 #define CBFS_FILE_ATTR_TAG_POSITION 0x42435350  /* PSCB */
 #define CBFS_FILE_ATTR_TAG_ALIGNMENT 0x42434c41 /* ALCB */
+#define CBFS_FILE_ATTR_TAG_IBB 0x32494242 /* Initial BootBlock */
 
 struct cbfs_file_attr_compression {
 	uint32_t tag;