RDMA/mlx5: Delete impossible GSI port check

GSI QP is created in the kernel with very strict parameters,
there is no possible way that port number will be wrong in
such flow.

Link: https://lore.kernel.org/r/20200427154636.381474-3-leon@kernel.org


Reviewed-by: Maor Gottlieb <maorg@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>