LU-9019 selftest: remove remaining cfs_time wrappers

LU-9019 selftest: remove remaining cfs_time wrappers

Remove remaining libcfs time wrappers from lnet selftest. Migrate
crp_stamp to nanoseconds and both timestamps nd_stamp, sn_start to
ktime. The move away from jiffies which can vary on platforms to
something that is the consistent on every node. This will ensure
that the reported results to the user will always be correct.

Test-Parameters: trivial testlist=lnet-selftest

Change-Id: Id8d1b195f690c69635de60dd9b501f6d97f90f4d
Signed-off-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-on: https://review.whamcloud.com/31041
Tested-by: Jenkins
Reviewed-by: Doug Oucharek <dougso@me.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>