rng-random: use error_setg_file_open()

Signed-off-by: Luiz Capitulino <lcapitulino@redhat.com>
Acked-by: Kevin Wolf <kwolf@redhat.com>

backends/rng-random.c

@@ -78,9 +78,8 @@ static void rng_random_opened(RngBackend *b, Error **errp)
                   "filename", "a valid filename");
     } else {
         s->fd = qemu_open(s->filename, O_RDONLY | O_NONBLOCK);
-
         if (s->fd == -1) {
-            error_set(errp, QERR_OPEN_FILE_FAILED, s->filename);
+            error_setg_file_open(errp, errno, s->filename);
         }
     }
 }