patman: rename main script to __main__.py

This allows running the package as a Python module, like e.g.:

    $ python -m patman

It also prevents Pytest from attempting to parse main.py, which
would cause errors.

Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Maxim Cournoyer <maxim.cournoyer@savoirfairelinux.com>
Fix up main.py in __init__.py:
Signed-off-by: Simon Glass <sjg@chromium.org>

tools/patman/__init__.py

@@ -1,6 +1,6 @@
 # SPDX-License-Identifier: GPL-2.0+
 
 __all__ = ['checkpatch', 'command', 'commit', 'control', 'cros_subprocess',
-           'func_test', 'get_maintainer', 'gitutil', 'main', 'patchstream',
+           'func_test', 'get_maintainer', 'gitutil', '__main__', 'patchstream',
            'project', 'series', 'setup', 'settings', 'terminal',
            'test_checkpatch', 'test_util', 'tools', 'tout']

tools/patman/patman

@@ -1 +1 @@
-main.py
+__main__.py