huawei driver references constants that don't exist

[Eric Harney]

Huawei driver code references constants that don't exist in the Cinder code, indicating likely problems for users of this driver. The pylint job detects these errors.

https://opendev.org/openstack/cinder/src/commit/3a47bc49/cinder/volume/drivers/huawei/huawei_conf.py#L197 (DEFAULT_LUN_TYPE)

https://opendev.org/openstack/cinder/src/commit/3a47bc49/cinder/volume/drivers/huawei/huawei_utils.py#L300 (LUN_INITIALIZING)

Presumably unit tests are passing because some of these constants are populated in the test rig:
https://opendev.org/openstack/cinder/src/commit/3a47bc49/cinder/tests/unit/volume/drivers/huawei/test_huawei_drivers.py#L2396

This may be due to a refactor project a couple of years ago that was partially completed:
https://review.opendev.org/c/openstack/cinder/+/638070