zorro: Make zorro_bus_type const

Since commit d492cc25 ("driver core: device.h: make struct
bus_type a const *"), the driver core can properly handle constant
struct bus_type, move the zorro_bus_type variable to be a constant
structure as well, placing it into read-only memory which can not be
modified at runtime.
Suggested-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Ricardo B. Marliere <ricardo@marliere.net>
Reviewed-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20240213-bus_cleanup-zorro-v1-1-388ceed8e7bd@marliere.netSigned-off-by: Geert Uytterhoeven <geert@linux-m68k.org>

drivers/zorro/zorro-driver.c

@@ -150,7 +150,7 @@ static int zorro_uevent(const struct device *dev, struct kobj_uevent_env *env)
 	return 0;
 }
 
-struct bus_type zorro_bus_type = {
+const struct bus_type zorro_bus_type = {
 	.name		= "zorro",
 	.dev_name	= "zorro",
 	.dev_groups	= zorro_device_attribute_groups,

drivers/zorro/zorro.h

@@ -4,7 +4,7 @@
      *  Zorro bus
      */
 
-extern struct bus_type zorro_bus_type;
+extern const struct bus_type zorro_bus_type;
 
 
 #ifdef CONFIG_ZORRO_NAMES