Since commit aed65af1cc2f ("drivers: make device_type const"), the driver
core can properly handle constant struct device_type. Move the
dsa_device_type, iax_device_type, idxd_wq_device_type, idxd_cdev_file_type,
idxd_cdev_device_type and idxd_group_device_type variables to be constant
structures as well, placing it into read-only memory which can not be
modified at runtime.
Cc: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Ricardo B. Marliere <ricardo@xxxxxxxxxxxx>