net: netdevsim: constify the struct device_type usage

Since commit aed65af1 ("drivers: make device_type const"), the driver
core can properly handle constant struct device_type. Move the
nsim_bus_dev_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>
Signed-off-by: Ricardo B. Marliere <ricardo@marliere.net>
Reviewed-by: Simon Horman <horms@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/netdevsim/bus.c

@@ -129,7 +129,7 @@ static void nsim_bus_dev_release(struct device *dev)
 		complete(&nsim_bus_devs_released);
 }
 
-static struct device_type nsim_bus_dev_type = {
+static const struct device_type nsim_bus_dev_type = {
 	.groups = nsim_bus_dev_attr_groups,
 	.release = nsim_bus_dev_release,
 };