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.

Lustre-change: https://review.whamcloud.com/33799
Lustre-commit: b24d69492b818457d9da0d6dce3adc0f91f18ec6

Change-Id: If100b4918bdcc8b24e72f37127048a32a808310f
Signed-off-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: Yang Sheng <ys@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-on: https://review.whamcloud.com/34781
Tested-by: Jenkins
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Olaf Faaland-LLNL <faaland1@llnl.gov>