block: rockchip: Staticize and constify driver ops

Set the ops structure as static const. The structure is not accessible
from outside of this driver and is not going to be modified at runtime.

Signed-off-by: Marek Vasut <marek.vasut+renesas@mailbox.org>
Acked-by: Quentin Schulz <quentin.schulz@cherry.de>
Reviewed-by: Simon Glass <sjg@chromium.org>

drivers/block/rkmtd.c

@@ -935,7 +935,7 @@ int rkmtd_detach_mtd(struct udevice *dev)
 	return 0;
 }
 
-struct rkmtd_ops rkmtd_ops = {
+static const struct rkmtd_ops rkmtd_ops = {
 	.attach_mtd	= rkmtd_attach_mtd,
 	.detach_mtd	= rkmtd_detach_mtd,
 };