Now that the nd_namespace_blk infrastructure is removed, delete all the
region machinery to coordinate provisioning aliased capacity between
PMEM and BLK.
Reviewed-by: Christoph Hellwig <hch@lst.de>
Link: https://lore.kernel.org/r/164688418803.2879318.1302315202397235855.stgit@dwillia2-desk3.amr.corp.intel.comSigned-off-by: Dan Williams <dan.j.williams@intel.com>