MFC r295022:

MFC r295022:

  nvd: add hw.nvd.delete_max tunable

  The NVMe specification does not define a maximum or optimal delete
  size, so technically max delete size is min(full size of namespace,
  2^32 - 1 LBAs).  A single delete operation for a multi-TB NVMe
  namespace though may take much longer to complete than the nvme(4)
  I/O timeout period.  So choose a sensible default here that is still
  suitably large to minimize the number of overall delete operations.

  This also fixes possible uint32_t overflow on initial TRIM operation
  for zpool create operations for NVMe namespaces with >4G LBAs.

Approved by:	re (glebius)
Sponsored by:	Intel

git-svn-id: svn://svn.freebsd.org/base/stable/10@295705 ccf9f872-aa2e-dd11-9fc8-001c23d0bc1f