net/mlx5: Add direct ST mode support for RDMA

net/mlx5: Add direct ST mode support for RDMA

Add support for direct ST mode where ST Table Location equals
PCI_TPH_LOC_NONE.

In that case, no steering table exists, the steering tag itself will be
used directly by the SW, FW, HW from the mkey.

This enables RDMA users to use the current exposed APIs to work in
direct mode.

Signed-off-by: Yishai Hadas <yishaih@nvidia.com>
Signed-off-by: Edward Srouji <edwards@nvidia.com>
Link: https://patch.msgid.link/20251027-st-direct-mode-v1-2-e0ad953866b6@nvidia.com
Signed-off-by: Leon Romanovsky <leon@kernel.org>