doc: FIT image: fix incorrect description of DT node unit address

The DT spec demands a unit-address in a node name to match the "reg"
property in that node. Newer dtc versions will throw warnings if this is
not the case.
Fix all occurences in the FIT image documentation files where this was not
observed, to not give bad examples to the reader.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>
diff --git a/doc/uImage.FIT/source_file_format.txt b/doc/uImage.FIT/source_file_format.txt
index 88663a1..d2793a1 100644
--- a/doc/uImage.FIT/source_file_format.txt
+++ b/doc/uImage.FIT/source_file_format.txt
@@ -102,15 +102,15 @@
     |
     o images
     | |
-    | o image@1 {...}
-    | o image@2 {...}
+    | o image-1 {...}
+    | o image-2 {...}
     | ...
     |
     o configurations
-      |- default = "conf@1"
+      |- default = "conf-1"
       |
-      o conf@1 {...}
-      o conf@2 {...}
+      o conf-1 {...}
+      o conf-2 {...}
       ...
 
 
@@ -142,7 +142,7 @@
 This node is a container node for component sub-image nodes. Each sub-node of
 the '/images' node should have the following layout:
 
- o image@1
+ o image-1
    |- description = "component sub-image description"
    |- data = /incbin/("path/to/data/file.bin")
    |- type = "sub-image type name"
@@ -152,8 +152,8 @@
    |- load = <00000000>
    |- entry = <00000000>
    |
-   o hash@1 {...}
-   o hash@2 {...}
+   o hash-1 {...}
+   o hash-2 {...}
    ...
 
   Mandatory properties:
@@ -183,14 +183,14 @@
     property of the root node. Mandatory for types: "standalone" and "kernel".
 
   Optional nodes:
-  - hash@1 : Each hash sub-node represents separate hash or checksum
+  - hash-1 : Each hash sub-node represents separate hash or checksum
     calculated for node's data according to specified algorithm.
 
 
 5) Hash nodes
 -------------
 
-o hash@1
+o hash-1
   |- algo = "hash or checksum algorithm name"
   |- value = [hash or checksum value]
 
@@ -212,8 +212,8 @@
 o configurations
   |- default = "default configuration sub-node unit name"
   |
-  o config@1 {...}
-  o config@2 {...}
+  o config-1 {...}
+  o config-2 {...}
   ...
 
 
@@ -231,7 +231,7 @@
 
 Each configuration has the following structure:
 
-o config@1
+o config-1
   |- description = "configuration description"
   |- kernel = "kernel sub-node unit name"
   |- ramdisk = "ramdisk sub-node unit name"