IB/mlx5, iser, isert: Add Signature API additions

IB/mlx5, iser, isert: Add Signature API additions

Expose more signature setting parameters. We modify the signature API
to allow usage of some new execution parameters relevant to data
integrity feature.

This patch modifies ib_sig_domain structure by:

- Deprecate DIF type in signature API (operation will
  be determined by the parameters alone, no DIF type awareness)
- Add APPTAG check bitmask (for input domain)
- Add REFTAG remap (increment) flag for each domain
- Add APPTAG/REFTAG escape options for each domain

The mlx5 driver is modified to follow the new parameters in HW
signature setup.

At the moment the callers (iser/isert) hard-code new parameters (by
DIF type). In the future, callers will retrieve them from the scsi
command structure.

Signed-off-by: Sagi Grimberg <sagig@mellanox.com>
Signed-off-by: Roland Dreier <roland@purestorage.com>