i3c: Make i3c_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 i3c_bus_type 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>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20240213-bus_cleanup-i3c-v1-1-403aea18f05a@marliere.netSigned-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

drivers/i3c/internals.h

@@ -10,7 +10,7 @@
 
 #include <linux/i3c/master.h>
 
-extern struct bus_type i3c_bus_type;
+extern const struct bus_type i3c_bus_type;
 
 void i3c_bus_normaluse_lock(struct i3c_bus *bus);
 void i3c_bus_normaluse_unlock(struct i3c_bus *bus);

drivers/i3c/master.c

@@ -335,7 +335,7 @@ static void i3c_device_remove(struct device *dev)
 	i3c_device_free_ibi(i3cdev);
 }
 
-struct bus_type i3c_bus_type = {
+const struct bus_type i3c_bus_type = {
 	.name = "i3c",
 	.match = i3c_device_match,
 	.probe = i3c_device_probe,