LU-8066 llite: move /proc/fs/lustre/llite/files* to sysfs

LU-8066 llite: move /proc/fs/lustre/llite/files* to sysfs

Move filestotal and filesfree files from /proc/fs/lustre/llite/*
to /sys/fs/lustre/llite/*/

This is a modified version of

Linux-commit: 7267ec0d8726c214aaf24ca9e8baebb443b0da75

due to the large amount of changes to the OpenSFS/Intel branch.

Change-Id: I84b6d6a0868058d60a83a0700f0389d3ba685ddb
Signed-off-by: Oleg Drokin <green@linuxhacker.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-on: https://review.whamcloud.com/32498
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Bobi Jam <bobijam@hotmail.com>
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>