RDMA/rtrs-clt: Raise MAX_SEGMENTS

As we can do fast memory registration on write, we can increase
the max_segments, default to 512K.

Link: https://lore.kernel.org/r/20210621055340.11789-5-jinpu.wang@ionos.com


Signed-off-by: Jack Wang <jinpu.wang@cloud.ionos.com>
Reviewed-by: Md Haris Iqbal <haris.iqbal@cloud.ionos.com>
Signed-off-by: Jason Gunthorpe <jgg@nvidia.com>