IB/mlx5: Clean mlx5_ib_mr_responder_pfault_handler() signature

In the function mlx5_ib_mr_responder_pfault_handler()

1. The parameter wqe is used as read-only so there is no need to pass it
   by reference.
2. Remove the unused argument pfault from list of arguments.

Signed-off-by: Moni Shoua <monis@mellanox.com>
Reviewed-by: Majd Dibbiny <majd@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>