binman: Allow easy importing of entry modules

At present entry modules can only be accessed using Entry.Lookup() or
Entry.Create(). Most of the time this is fine, but sometimes a module
needs to provide constants or helper functions useful to other modules.
It is easier in this case to use 'import'.

Add an __init__ file to permit this.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/binman/entry.py b/tools/binman/entry.py
index 00bb1d1..a04e149 100644
--- a/tools/binman/entry.py
+++ b/tools/binman/entry.py
@@ -513,6 +513,8 @@
             modules.remove('_testing')
         missing = []
         for name in modules:
+            if name.startswith('__'):
+                continue
             module = Entry.Lookup(name, name)
             docs = getattr(module, '__doc__')
             if test_missing == name: