LU-9859 libcfs: replace cfs_srand() calls with add_device_randomness().

LU-9859 libcfs: replace cfs_srand() calls with add_device_randomness().

The only places that cfs_srand is called, the random bits are
mixed with bits from get_random_bytes().  So it is equally effective
to add entropy to either pool.
So we can replace calls to cfs_srand() with calls that add the
entropy with add_device_randomness().  That function adds time-based
entropy, so we can discard the ktime_get_ts64 calls.

One location in lustre_handles.c only adds time based
entropy. This cannot improve the entropy provided by
get_random_bytes(), so just discard that call.

Linux-commit: 30f4236aafa81722490e74ded48a9fb2aff013ab

Change-Id: If1a8ffad05fcc89272136949300f6512dca39704
Signed-off-by: NeilBrown <neilb@suse.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-on: https://review.whamcloud.com/34170
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: Jenkins
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Ben Evans <bevans@cray.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>