staging: lustre: libcfs: replace direct HZ access with kernel APIs

staging: lustre: libcfs: replace direct HZ access with kernel APIs

On some customers' systems, the 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 the libcfs module.

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/11993
Reviewed-by: Nathaniel Clark <nathaniel.l.clark@intel.com>
Reviewed-by: James Simmons <uja.ornl@gmail.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>