binman: Deal with mkeficapsule being missing

Tools cannot be assumed to be present. Add a check for this with the
mkeficpasule tool.

Signed-off-by: Simon Glass <sjg@chromium.org>
Fixes: b617611b27 ("binman: capsule: Add support for generating...")

tools/binman/etype/efi_capsule.py

@@ -150,6 +150,10 @@ class Entry_efi_capsule(Entry_section):
         if ret is not None:
             os.remove(payload)
             return tools.read_file(capsule_fname)
+        else:
+            # Bintool is missing; just use the input data as the output
+            self.record_missing_bintool(self.mkeficapsule)
+            return data
 
     def AddBintools(self, btools):
         self.mkeficapsule = self.AddBintool(btools, 'mkeficapsule')