moxtet: mark moxtet_bus_type as const

Now that the driver core can properly handle constant struct bus_type,
move the moxtet_bus_type to be a constant structure as well, placing it
into read-only memory which can not be modified at runtime.

Cc: Marek Behún <kabel@kernel.org>
Link: https://lore.kernel.org/r/2023121939-written-guru-db83@gregkhSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/bus/moxtet.c

@@ -102,7 +102,7 @@ static int moxtet_match(struct device *dev, struct device_driver *drv)
 	return 0;
 }
 
-static struct bus_type moxtet_bus_type = {
+static const struct bus_type moxtet_bus_type = {
 	.name		= "moxtet",
 	.dev_groups	= moxtet_dev_groups,
 	.match		= moxtet_match,