LU-13344 lnet: stop using struct timeval

LU-13344 lnet: stop using struct timeval

The struct timeval is not 2038 safe so the Linux kernel is moving
away from its use. The use of rpe_stamp hasn't been used since
Lustre 2.2 so remove the userland use of this field. This frees
use to change rpe_stamp to an equivalent struct timespec64 for
future use. Greatly simplify lnet_sock_[read|write] by using
jiffies values of sk_sndtimeo, sk_rcvtimeo cached in struct sock.

Change-Id: Ib58193756ec4a526e55bc810c05abd3920b2b269
Signed-off-by: James Simmons <jsimmons@infradead.org>
Reviewed-on: https://review.whamcloud.com/38105
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Shaun Tancheff <shaun.tancheff@hpe.com>
Tested-by: Maloo <maloo@whamcloud.com>