udev-rules: pass the right error variable

(cherry picked from commit 75c64e5)

Author: dtardon

src/udev/udev-rules.c

@@ -1538,7 +1538,7 @@ int udev_rules_parse_file(UdevRules *rules, const char *filename, bool extra_che
 
         r = hashmap_put_stats_by_path(&rules->stats_by_path, filename, &st);
         if (r < 0)
-                return log_warning_errno(errno, "Failed to save stat for %s, ignoring: %m", filename);
+                return log_warning_errno(r, "Failed to save stat for %s, ignoring: %m", filename);
 
         (void) fd_warn_permissions(filename, fileno(f));