LU-7850 gnilnd: Fix niov calculation with offset kiov

LU-7850 gnilnd: Fix niov calculation with offset kiov

The niov calculation in kgnilnd_setup_immediate_buffer() did not take
into account an offset kiov which can cause it to map one less page
than needed.
Add in the kiov_offset to the calculation.
Ran patched lnet_selftest that allows specifying an offset and
observed correct behavior.

Signed-off-by: Chris Horn <hornc@cray.com>
Change-Id: Id3d500d178841aa803c35bcbb7b56fd13b3fc1b0
Reviewed-on: http://review.whamcloud.com/18793
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Doug Oucharek <doug.s.oucharek@intel.com>
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>