vio: move to_vio_dev() to use container_of_const()

The driver core is changing to pass some pointers as const, so move
to_vio_dev() to use container_of_const() to handle this change.
to_vio_dev() now properly keeps the const-ness of the pointer passed
into it, while as before it could be lost.

Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Nicholas Piggin <npiggin@gmail.com>
Cc: Christophe Leroy <christophe.leroy@csgroup.eu>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: "Gustavo A. R. Silva" <gustavoars@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Link: https://lore.kernel.org/r/20230111113018.459199-9-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

arch/sparc/include/asm/vio.h

@@ -488,10 +488,7 @@ static inline struct vio_driver *to_vio_driver(struct device_driver *drv)
 	return container_of(drv, struct vio_driver, driver);
 }
 
-static inline struct vio_dev *to_vio_dev(struct device *dev)
-{
-	return container_of(dev, struct vio_dev, dev);
-}
+#define to_vio_dev(__dev)	container_of_const(__dev, struct vio_dev, dev)
 
 int vio_ldc_send(struct vio_driver_state *vio, void *data, int len);
 void vio_link_state_change(struct vio_driver_state *vio, int event);