net: hsr: constify the struct device_type usage

Since commit aed65af1cc ("drivers: make device_type const"), the driver
core can properly handle constant struct device_type. Move the hsr_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>

net/hsr/hsr_device.c

@@ -467,7 +467,7 @@ static const struct net_device_ops hsr_device_ops = {
 	.ndo_set_rx_mode = hsr_set_rx_mode,
 };
 
-static struct device_type hsr_type = {
+static const struct device_type hsr_type = {
 	.name = "hsr",
 };