ubifs: Format changes for authentication support

This patch adds the changes to the on disk format needed for
authentication support. We'll add:

* a HMAC covering super block node
* a HMAC covering the master node
* a hash over the root index node to the master node
* a hash over the LPT to the master node
* a flag to the filesystem flag indicating the filesystem is
  authenticated
* an authentication node necessary to authenticate the nodes written
  to the journal heads while they are written.
* a HMAC of a well known message to the super block node to be able
  to check if the correct key is provided

And finally, not visible in this patch, nevertheless explained here:

* hashes over the referenced child nodes in each branch of a index node

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Signed-off-by: Richard Weinberger <richard@nod.at>
diff --git a/fs/ubifs/debug.c b/fs/ubifs/debug.c
index 564e330..c49ff50 100644
--- a/fs/ubifs/debug.c
+++ b/fs/ubifs/debug.c
@@ -165,6 +165,8 @@ const char *dbg_ntype(int type)
 		return "commit start node";
 	case UBIFS_ORPH_NODE:
 		return "orphan node";
+	case UBIFS_AUTH_NODE:
+		return "auth node";
 	default:
 		return "unknown node";
 	}
@@ -542,6 +544,10 @@ void ubifs_dump_node(const struct ubifs_info *c, const void *node)
 			       (unsigned long long)le64_to_cpu(orph->inos[i]));
 		break;
 	}
+	case UBIFS_AUTH_NODE:
+	{
+		break;
+	}
 	default:
 		pr_err("node type %d was not recognized\n",
 		       (int)ch->node_type);