reduce iSERT Max IO size

[Krishnamraju Eraparaju <krishna2@xxxxxxxxxxx>]

Hi,

Please reduce the Max IO size to 1MiB(256 pages), at iSER Target.
The PBL memory consumption has increased significantly after increasing
the Max IO size to 16MiB(with commit:317000b926b07c).
Due to the large MR pool, the max no.of iSER connections(On one variant
of Chelsio cards) came down to 9, before it was 250.
NVMe-RDMA target also uses 1MiB max IO size.

Thanks,
Krishnam Raju.