u_boot_pylib: Tidy up quoting of cc and to

The current approach to calling 'git send-email' puts double quotes
around each email address to ensure that it will pass the shell
correctly. This is a bit cumbersome and requires using a shell to sort
it all out.

Drop the quotes and use command.run() instead, to simplify things. This
will also make it possible to (later) set the current directory.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/patman/func_test.py b/tools/patman/func_test.py
index 3a34302..7f9175e 100644
--- a/tools/patman/func_test.py
+++ b/tools/patman/func_test.py
@@ -292,7 +292,7 @@
         self.assertEqual('      Cc:  %s' % mel, next(lines))
         self.assertEqual('      Cc:  %s' % rick, next(lines))
         expected = ('Git command: git send-email --annotate '
-                    '--in-reply-to="%s" --to "u-boot@lists.denx.de" '
+                    '--in-reply-to="%s" --to u-boot@lists.denx.de '
                     '--cc "%s" --cc-cmd "%s send --cc-cmd %s" %s %s'
                     % (in_reply_to, stefan, sys.argv[0], cc_file, cover_fname,
                        ' '.join(args)))