LU-8066 utils: have llapi_target_iterate use sysfs tree

LU-8066 utils: have llapi_target_iterate use sysfs tree

Update llapi_target_iterate() to not use 'devices' but collect the
data from the lustre sysfs tree itself.

Change-Id: If100b4918bdcc8b24e72f37127048a32a808310f
Signed-off-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-on: https://review.whamcloud.com/33799
Tested-by: Jenkins
Reviewed-by: Yang Sheng <ys@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>