nvme: move blk_integrity_unregister into nvme_init_integrity

Move uneregistering the existing integrity profile into the helper
dealing with all the other integrity / metadata setup.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Max Gurtovoy <mgurtovoy@nvidia.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>