Implement ZBC host-aware device model emulation. The main changes from the
host-managed emulation are the device type (TYPE_DISK is used), relaxation
of access checks for read and write operations and different handling of a
sequential write preferred zone write pointer as mandated by the ZBC r05
specifications.

To facilitate the implementation and avoid a lot of "if" statement, the
zmodel field is added to the device information and the z_type field to the
zone state data structure.

Link: https://lore.kernel.org/r/20200422104221.378203-8-damien.lemoal@wdc.comTested-by: Douglas Gilbert <dgilbert@interlog.com>
Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>