RDMA/core: Use simplified list_for_each

While traversing client_data_list in following conditions, linked list is
only read, no elements of the list are removed.  Therefore, use
list_for_each_entry(), instead of list_for_each_safe().

Signed-off-by: Parav Pandit <parav@mellanox.com>
Reviewed-by: Daniel Jurgens <danielj@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>