scsi: iscsi: Make iscsi_flashnode_bus const

Now that the driver core can properly handle constant struct bus_type, move
the iscsi_flashnode_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>
Link: https://lore.kernel.org/r/20240203-bus_cleanup-scsi-v1-2-6f552fb24f71@marliere.netReviewed-by: Lee Duncan <lduncan@suse.com>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/scsi_transport_iscsi.c

@@ -1201,7 +1201,7 @@ static const struct device_type iscsi_flashnode_conn_dev_type = {
 	.release = iscsi_flashnode_conn_release,
 };
 
-static struct bus_type iscsi_flashnode_bus;
+static const struct bus_type iscsi_flashnode_bus;
 
 int iscsi_flashnode_bus_match(struct device *dev,
 				     struct device_driver *drv)
@@ -1212,7 +1212,7 @@ int iscsi_flashnode_bus_match(struct device *dev,
 }
 EXPORT_SYMBOL_GPL(iscsi_flashnode_bus_match);
 
-static struct bus_type iscsi_flashnode_bus = {
+static const struct bus_type iscsi_flashnode_bus = {
 	.name = "iscsi_flashnode",
 	.match = &iscsi_flashnode_bus_match,
 };