IB/mlx5: Set and get correct qp_num for a DCT QP

IB/mlx5: Set and get correct qp_num for a DCT QP

When a DCT QP is created on an active lag, it's dctc.port is assigned
in a round-robin way, which is from 1 to dev->lag_port. In this case
when querying this QP, we may get qp_attr.port_num > 2.
Fix this by setting qp->port when modifying a DCT QP, and read port_num
from qp->port instead of dctc.port when querying it.

Fixes: 7c4b1ab9f167 ("IB/mlx5: Add DCT RoCE LAG support")
Signed-off-by: Mark Zhang <markzhang@nvidia.com>
Reviewed-by: Maher Sanalla <msanalla@nvidia.com>
Link: https://patch.msgid.link/94c76bf0adbea997f87ffa27674e0a7118ad92a9.1737290358.git.leon@kernel.org
Signed-off-by: Leon Romanovsky <leon@kernel.org>