binman: Remove '/images/' fragment from FIT subentry paths

Binman FIT entry nodes describe their subentries in an 'images' subnode,
same as how they would be written for the mkimage executable. The entry
type initially manually managed its subentries keyed by their node paths
relative to its base node. It was later converted to a proper section
while still keeping the same keys for subentries.

These subentry keys of sections are used as path fragments, so they must
not contain the path separator character '/'. Otherwise, they won't be
addressable by binman extract/replace commands. Change these keys from
the '/images/foo' forms to the subentry node names. Extend the simple
FIT tests to check for this.

Signed-off-by: Alper Nebi Yasak <alpernebiyasak@gmail.com>
diff --git a/tools/binman/etype/fit.py b/tools/binman/etype/fit.py
index e040771..0357198 100644
--- a/tools/binman/etype/fit.py
+++ b/tools/binman/etype/fit.py
@@ -384,7 +384,8 @@
                 entry.ReadNode()
                 # The hash subnodes here are for mkimage, not binman.
                 entry.SetUpdateHash(False)
-                self._entries[rel_path] = entry
+                image_name = rel_path[len('/images/'):]
+                self._entries[image_name] = entry
 
             for subnode in node.subnodes:
                 _add_entries(base_node, depth + 1, subnode)
@@ -630,7 +631,8 @@
 
             has_images = depth == 2 and in_images
             if has_images:
-                entry = self._priv_entries[rel_path]
+                image_name = rel_path[len('/images/'):]
+                entry = self._priv_entries[image_name]
                 data = entry.GetData()
                 fsw.property('data', bytes(data))
 
@@ -643,12 +645,12 @@
                     # fsw.add_node() or _add_node() for it.
                     pass
                 elif self.GetImage().generate and subnode.name.startswith('@'):
-                    entry = self._priv_entries.get(subnode_path)
+                    entry = self._priv_entries.get(subnode.name)
                     _gen_node(base_node, subnode, depth, in_images, entry)
                     # This is a generator (template) entry, so remove it from
                     # the list of entries used by PackEntries(), etc. Otherwise
                     # it will appear in the binman output
-                    to_remove.append(subnode_path)
+                    to_remove.append(subnode.name)
                 else:
                     with fsw.add_node(subnode.name):
                         _add_node(base_node, depth + 1, subnode)
@@ -693,7 +695,8 @@
         fdt = Fdt.FromData(self.GetData())
         fdt.Scan()
 
-        for path, section in self._entries.items():
+        for image_name, section in self._entries.items():
+            path = f"/images/{image_name}"
             node = fdt.GetNode(path)
 
             data_prop = node.props.get("data")
diff --git a/tools/binman/ftest.py b/tools/binman/ftest.py
index c9a8209..0e77358 100644
--- a/tools/binman/ftest.py
+++ b/tools/binman/ftest.py
@@ -3764,6 +3764,13 @@
         self.assertEqual(len(kernel_data), int(data_sizes[0].split()[0]))
         self.assertEqual(len(fdt1_data), int(data_sizes[1].split()[0]))
 
+        # Check if entry listing correctly omits /images/
+        image = control.images['image']
+        fit_entry = image.GetEntries()['fit']
+        subentries = list(fit_entry.GetEntries().keys())
+        expected = ['kernel', 'fdt-1']
+        self.assertEqual(expected, subentries)
+
     def testSimpleFit(self):
         """Test an image with a FIT inside"""
         data = self._DoReadFile('161_fit.dts')