LU-8066 mdt: migrate procfs files to sysfs

LU-8066 mdt: migrate procfs files to sysfs

Move the simple one item MDT proc files to sysfs. For all the
proc files for the HSM directory move them to both sysfs and the
more complex ones to debugfs since HSM is managed by admins.

Change-Id: I4603d04853e82c29059dfc043b3ddc75757ffe27
Signed-off-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-on: https://review.whamcloud.com/34779
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Alex Zhuravlev <bzzz@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>