bootstd: rauc: Don't null bootflow->bootmeth_priv

Don't null bootflow->bootmeth_priv, as the private struct is freed later
on by the bootflow.

Signed-off-by: Martin Schwan <m.schwan@phytec.de>
Tested-by: Wadim Egorov <w.egorov@phytec.de>

boot/bootmeth_rauc.c

@@ -193,7 +193,6 @@ static int distro_rauc_read_bootflow(struct udevice *dev, struct bootflow *bflow
 		}
 		free(priv);
 		free(boot_order_copy);
-		bflow->bootmeth_priv = NULL;
 		return ret;
 	}