LU-4730 utils: lctl get_param, set_param cleanup

LU-4730 utils: lctl get_param, set_param cleanup

Cleanup "lctl get_param" and "lctl set_param" code and error handling.
Deny "parameters" with embedded relative paths to avoid strangeness.
Return an error consistently if multiple parameters are set but the
last one did not fail.  Remove deprecated full-path handling.

Signed-off-by: Andreas Dilger <andreas.dilger@intel.com>
Change-Id: I1004b5b4da4dc9b5825ef498758e248ed52f4141
Reviewed-on: http://review.whamcloud.com/9545
Tested-by: Jenkins
Reviewed-by: John L. Hammond <john.hammond@intel.com>
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: James Simmons <uja.ornl@gmail.com>
Reviewed-by: Chao Wang <chao.ornl@gmail.com>
Reviewed-by: frank zago <fzago@cray.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>