LU-4423 lnet: switch to kernel_sendmsg()

LU-4423 lnet: switch to kernel_sendmsg()

Upstream commit by Al Viro:
lustre: switch to kernel_sendmsg()
(casts are due to misannotations in lustre; it uses iovec where kvec
would be correct type; too much noise to properly annotate right now).

Linux-commit: 480f40de91e74190281309fd0ecb2d0414603c2e

Change-Id: I1f6e27cd158bd3e15d06b88d3e973dc7f99a5e60
Signed-off-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: James Simmons <uja.ornl@gmail.com>
Reviewed-on: http://review.whamcloud.com/10125
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Reviewed-by: Liang Zhen <liang.zhen@intel.com>
Reviewed-by: Isaac Huang <he.huang@intel.com>