patman: Add a -m option to avoid copying the maintainers

The get_maintainers script is a useful default, but sometimes is copies
too many people, or takes a long time to run.

Add an option to disable it and update the README.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/patman/patman.py b/tools/patman/patman.py
index 2ab6b35..6c6473e 100755
--- a/tools/patman/patman.py
+++ b/tools/patman/patman.py
@@ -32,6 +32,9 @@
 parser.add_option('-i', '--ignore-errors', action='store_true',
        dest='ignore_errors', default=False,
        help='Send patches email even if patch errors are found')
+parser.add_option('-m', '--no-maintainers', action='store_false',
+       dest='add_maintainers', default=True,
+       help="Don't cc the file maintainers automatically")
 parser.add_option('-n', '--dry-run', action='store_true', dest='dry_run',
        default=False, help="Do a dry run (create but don't email patches)")
 parser.add_option('-p', '--project', default=project.DetectProject(),
@@ -142,7 +145,8 @@
         ok = True
 
     cc_file = series.MakeCcFile(options.process_tags, cover_fname,
-                                not options.ignore_bad_tags)
+                                not options.ignore_bad_tags,
+                                options.add_maintainers)
 
     # Email the patches out (giving the user time to check / cancel)
     cmd = ''