IB/mlx5: Remove useless check in ODP handler

When handling an ODP event for a receive WQE in SRQ the target QP is
unknown. Therefore, it is wrong to ask if QP has a SRQ in the page-fault
handler.

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>