LU-4423 lnet: don't use iovec instead of kvec

LU-4423 lnet: don't use iovec instead of kvec

Replace struct iovec with struct kvec.

Linux commit: f351bad2b4b4bb74810ad4f127f6602e2d2ae403

Change-Id: Ib7bb49069e42ca82d66a149617361c73ee4d710d
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-on: http://review.whamcloud.com/17205
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Reviewed-by: Frank Zago <fzago@cray.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>