LU-8125 nrs: pol_arg should be copied after the policy starts

LU-8125 nrs: pol_arg should be copied after the policy starts

NRS policy->pol_arg should be copied to a given policy argument
after the policy starts, otherwise a wrong argument will be saved
and it will cause LBUG when we run "lctl get_param" to get NRS
policy.
sanityn.sh test_77h is added to verify this patch.

Signed-off-by: Emoly Liu <emoly.liu@intel.com>
Change-Id: I5a015bb44fa88f69a4d5347cc2721eb72a57c8ad
Reviewed-on: http://review.whamcloud.com/20164
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Li Xi <lixi@ddn.com>
Reviewed-by: Henri Doreau <henri.doreau@cea.fr>
Reviewed-by: Jean-Baptiste Riaux <riaux.jb@intel.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>