RDMA/srpt: Reduce max_recv_sge to 1

Since srpt_post_recv() always sets num_sge to 1, reduce the max_recv_sge
parameter that is used at queue pair allocation time to 1.

Link: https://lore.kernel.org/r/20200525172212.14413-4-bvanassche@acm.org


Signed-off-by: Bart Van Assche <bvanassche@acm.org>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>