bus: sunxi-rsb: Fix error handling in sunxi_rsb_init()

The sunxi_rsb_init() returns the platform_driver_register() directly
without checking its return value, if platform_driver_register() failed,
the sunxi_rsb_bus is not unregistered.
Fix by unregister sunxi_rsb_bus when platform_driver_register() failed.

Fixes: d787dcdb ("bus: sunxi-rsb: Add driver for Allwinner Reduced Serial Bus")
Signed-off-by: Yuan Can <yuancan@huawei.com>
Reviewed-by: Jernej Skrabec <jernej.skrabec@gmail.com>
Link: https://lore.kernel.org/r/20221123094200.12036-1-yuancan@huawei.comSigned-off-by: Jernej Skrabec <jernej.skrabec@gmail.com>

drivers/bus/sunxi-rsb.c

@@ -857,7 +857,13 @@ static int __init sunxi_rsb_init(void)
 		return ret;
 	}
 
-	return platform_driver_register(&sunxi_rsb_driver);
+	ret = platform_driver_register(&sunxi_rsb_driver);
+	if (ret) {
+		bus_unregister(&sunxi_rsb_bus);
+		return ret;
+	}
+
+	return 0;
 }
 module_init(sunxi_rsb_init);