LU-8066 ptlrpc: migrate ptlrpc proc files to sysfs

LU-8066 ptlrpc: migrate ptlrpc proc files to sysfs

move procfs high_priority_ratio file to sysfs

Move ptlrpc service high_priority_ratio entry from procfs to sysfs.
Currently in use only by ldlm callback service only in
/sys/fs/lustre/ldlm/services/ldlm_cbd

Linux-commit: b40881e579588360242bd3f8f79f978d2a871e0e

move procfs threads* files to sysfs

Move ptlrpc service threads_min, threads_max and threads_running
entries from procfs to sysfs. Currently in use only by ldlm
callback service only in /sys/fs/lustre/ldlm/services/ldlm_cbd

Linux-commit: 673a6796f290fe8079af6a688f20c87e7416bba5

Add infrastructure for sysfs migration

Added necessary plumbing for ptlrpc sysfs integration for registered
services, sysfs directory registration.

Linux-commit: 328676f823b49741675f8ae47643669a31c79558

Add support for server side for this change.

Change-Id: Ia82a11dabd672a0c36083d06303aff2a81f3c48f
Signed-off-by: James Simmons <uja.ornl@yahoo.com>
Signed-off-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Reviewed-on: https://review.whamcloud.com/25073
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Fan Yong <fan.yong@intel.com>
Reviewed-by: Dmitry Eremin <dmitry.eremin@intel.com>