When the data and protection are interleaved in the memory domain, no
need to expand the mkey total length.

At the moment no Linux user works (iSER initiator & target) in
interleaved mode. This may change in the future as for SCSI
pass-through devices there is no real point in target performing
de-interleaving and re-interleaving of the protection data in the PT
stage. Regardless, signature verbs support this mode.
Signed-off-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>