accel: constify the struct device_type usage

Since commit aed65af ("drivers: make device_type const"), the driver
core can properly handle constant struct device_type. Move the
accel_sysfs_device_minor 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: Oded Gabbay <ogabbay@kernel.org>
Signed-off-by: Oded Gabbay <ogabbay@kernel.org>

drivers/accel/drm_accel.c

@@ -23,7 +23,7 @@ static struct idr accel_minors_idr;
 
 static struct dentry *accel_debugfs_root;
 
-static struct device_type accel_sysfs_device_minor = {
+static const struct device_type accel_sysfs_device_minor = {
 	.name = "accel_minor"
 };