LU-165: Support privileged ports in the o2iblnd driver.

It is highly recommended that you have a version of the
IB verbs driver that provides the rdma_set_reuseaddr() function.
Otherwise you may run out of privileged ports.

In this version of the patch, one may separately decide whether
privileged ports will be required for passively accepted connections
(require_privileged_port) and whether privileged ports will be used
for activitely initiated connections (use_privileged_port).

Original patch by Ira Weiny.

Change-Id: Id3600094b08784be6e82b224cf510460f69d4dd6
Signed-off-by: Christopher J. Morrone <morrone2@llnl.gov>
Reviewed-on: http://review.whamcloud.com/366
Tested-by: Hudson
Reviewed-by: Oleg Drokin <green@whamcloud.com>