LU-12621 o2iblnd: cache max_qp_wr

LU-12621 o2iblnd: cache max_qp_wr

When creating the device the maximum number of work requests per qp
which can be allocated is already known. Cache that internally,
and when creating the qp make sure the qp's max_send_wr does not
exceed that max. If it does then cap max_send_wr to max_qp_wr.
Recalculate the connection's queue depth based on the max_qp_wr.

Test-Parameter: nettype=o2ib
Signed-off-by: Amir Shehata <ashehata@whamcloud.com>
Change-Id: I6d9a642d03633264f5f14445a051dd14515709c1
Reviewed-on: https://review.whamcloud.com/36073
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Doug Oucharek <dougso@me.com>
Reviewed-by: Olaf Weber <olaf.weber@hpe.com>
Reviewed-by: James Simmons <jsimmons@infradead.org>
Reviewed-by: Oleg Drokin <green@whamcloud.com>