kmem cache fixes

The mempool names was stored in a wron place.
Add counters for initial and primay pools.

Signed-off-by: Shlomo Pongratz <shlomop@mellanox.com>
option force rdma write for small response buffers

A requester can insist on receiving the response via RDMA
regardless the expected response size. Currently small responses
are send via post send which implies copy operation form the
arbitrary receive buffer to the user buffer.

Signed-off-by: Shlomo Pongratz <shlomop@mellanox.com>