LU-8066 osp: migrate from proc to sysfs

LU-8066 osp: migrate from proc to sysfs

Move the osp module from using proc for most single value files
to sysfs. Create the default attrs for dt_devices which can be
used for other server side devices.

Change-Id: I51fef51287585b38a1aff80d8edf986583c54a14
Signed-off-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-on: https://review.whamcloud.com/32377
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Alex Zhuravlev <bzzz@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: John L. Hammond <jhammond@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>