tools: Add init files for Python tools

Add some empty __init__ files for binman, buildman and dtoc so that
pylint is able to recognise these as Python modules and produce more
useful pylint output.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/binman/__init__.py b/tools/binman/__init__.py
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/tools/binman/__init__.py
diff --git a/tools/buildman/__init__.py b/tools/buildman/__init__.py
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/tools/buildman/__init__.py
diff --git a/tools/dtoc/__init__.py b/tools/dtoc/__init__.py
new file mode 100644
index 0000000..e69de29
--- /dev/null
+++ b/tools/dtoc/__init__.py