SDDM-config: allow poorly formatted SDDM config

SDDM itself doesn't trip over duplicate sections or keys, but
the Python config-parser does (in strict mode). Relax a bit.

FIXES #579

src/modules/displaymanager/main.py

@@ -318,7 +318,7 @@ def set_autologin(username,
         # Systems with Sddm as Desktop Manager
         sddm_conf_path = os.path.join(root_mount_point, "etc/sddm.conf")
 
-        sddm_config = configparser.ConfigParser()
+        sddm_config = configparser.ConfigParser(strict=False)
         # Make everything case sensitive
         sddm_config.optionxform = str