bus: sunxi-rsb: make sunxi_rsb_bus const

Now that the driver core can properly handle constant struct bus_type,
move the sunxi_rsb_bus variable to be a constant structure as well,
placing it into read-only memory which can not be modified at runtime.

Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ricardo B. Marliere <ricardo@marliere.net>
Acked-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20240204-bus_cleanup-bus-v1-1-bda309c4b829@marliere.netSigned-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>

drivers/bus/sunxi-rsb.c

@@ -128,7 +128,7 @@ struct sunxi_rsb {
 };
 
 /* bus / slave device related functions */
-static struct bus_type sunxi_rsb_bus;
+static const struct bus_type sunxi_rsb_bus;
 
 static int sunxi_rsb_device_match(struct device *dev, struct device_driver *drv)
 {
@@ -177,7 +177,7 @@ static int sunxi_rsb_device_modalias(const struct device *dev, struct kobj_ueven
 	return of_device_uevent_modalias(dev, env);
 }
 
-static struct bus_type sunxi_rsb_bus = {
+static const struct bus_type sunxi_rsb_bus = {
 	.name		= RSB_CTRL_NAME,
 	.match		= sunxi_rsb_device_match,
 	.probe		= sunxi_rsb_device_probe,