dm crypt: Enable zoned block device support

Enable support for zoned block devices. This is done by:
1) implementing the target report_zones method.
2) adding the DM_TARGET_ZONED_HM flag to the target features.
3) setting DM_CRYPT_NO_WRITE_WORKQUEUE flag to avoid IO
   processing via workqueue.
4) Introducing inline write encryption completion to preserve write
   ordering.

The last point is implemented by introducing the internal flag
DM_CRYPT_WRITE_INLINE. When set, kcryptd_crypt_write_convert() always
waits inline for the completion of a write request encryption if the
request is not already completed once crypt_convert() returns.
Completion of write request encryption is signaled using the
restart completion by kcryptd_async_done(). This mechanism allows
using ciphers that have an asynchronous implementation, isolating
dm-crypt from any potential request completion reordering for these
ciphers.

Signed-off-by: Damien Le Moal <damien.lemoal@wdc.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>