Add controller-based data-at-rest encryption compatibility
to ioaccel2 path (HP SSD Smart Path).

Encryption feature requires driver to supply additional fields
for encryption enable, tweak index, and data encryption key index
in the ioaccel2 request structure.

Encryption enable flag and data encryption key index come from
raid_map data structure from raid offload command.

During ioaccel2 submission, check device structure's raid map to see if
encryption is enabled for the device. If so, call new function below.

Add function set_encrypt_ioaccel2 to set encryption flag, data encryption key
index, and calculate tweak value from request's logical block address.
Signed-off-by: Scott Teel <scott.teel@hp.com>
Signed-off-by: Stephen M. Cameron <scameron@beardog.cce.hp.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>