LU-9019 libcfs: avoid using HZ and msecs_to_jiffies()

LU-9019 libcfs: avoid using HZ and msecs_to_jiffies()

HZ is a constant selected with the configuration of the kernel
and msecs_to_jiffies() is a inline function in jiffies.h. Because
we are out of tree that means prebuilt lustre packages could be
installed on a node with different values which impact the
behavior of the file system. This was addressed earlier but
regression have crept back in. Fix up all those instances by
replacing msec_to_jiffies() and HZ with cfs_time_seconds() which
translates seconds to jiffies with nsec_to_jiffies(). Add to
spelling.txt to avoid new regressions.

Change-Id: Ie13efe83774db498bb5475ed47a057bbd42d47bf
Signed-off-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-on: https://review.whamcloud.com/35520
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Yang Sheng <ys@whamcloud.com>
Reviewed-by: Jian Yu <yujian@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>