staging: lustre: replace direct HZ access with kernel APIs

staging: lustre: replace direct HZ access with kernel APIs

On some customer's systems, kernel was compiled with HZ defined to
100, instead of 1000. This improves performance for HPC applications.
However, to use these systems with Lustre, customers have to re-build
Lustre for the kernel because Lustre directly uses the defined
constant HZ.

Since kernel 2.6.21, some non-HZ dependent timing APIs become non-
inline functions, which can be used in Lustre codes to replace the
direct HZ access.

These kernel APIs include:
  jiffies_to_msecs()
  jiffies_to_usecs()
  jiffies_to_timespec()
  msecs_to_jiffies()
  usecs_to_jiffies()
  timespec_to_jiffies()

And here are some samples of the replacement:
  HZ            -> msecs_to_jiffies(MSEC_PER_SEC)
  n * HZ        -> msecs_to_jiffies(n * MSEC_PER_SEC)
  HZ / n        -> msecs_to_jiffies(MSEC_PER_SEC / n)
  n / HZ        -> jiffies_to_msecs(n) / MSEC_PER_SEC
  n / HZ * 1000 -> jiffies_to_msecs(n)

This patch replaces the direct HZ access in lustre modules.

Signed-off-by: Jian Yu <jian.yu@intel.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-5443
Reviewed-on: http://review.whamcloud.com/12052
Reviewed-by: Bob Glossman <bob.glossman@intel.com>
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>
Reviewed-by: James Simmons <uja.ornl@gmail.com>
Reviewed-by: Nathaniel Clark <nathaniel.l.clark@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>