staging: lustre: libcfs: calculate crypto performance using pages

Use alloc_page() and use cfs_crypto_hash_update_page()
to compute the hash instead of cfs_crypto_hash_digest(), since
tgt_checksum_bulk() computes the hash by page anyway.

Signed-off-by: Andreas Dilger <andreas.dilger@intel.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-5279
Reviewed-on: http://review.whamcloud.com/10982


Reviewed-by: John L. Hammond <john.hammond@intel.com>
Reviewed-by: James Simmons <uja.ornl@gmail.com>
Reviewed-by: Alexander Boyko <alexander_boyko@xyratex.com>
Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>