LU-14543 target: prevent overflowing of tgd->tgd_tot_granted

LU-14543 target: prevent overflowing of tgd->tgd_tot_granted

If tgd->tgd_tot_granted < ted->ted_grant then there should not be:
   tgd->tgd_tot_granted -= ted->ted_grant;
which breaks tgd->tgd_tot_granted.
In case of obvious ted->ted_grant damage, recalculate
tgd->tgd_tot_granted using list of exports.

The same change is made for tgd->tgd_tot_dirty.

This patch also adds sanity check for exp->exp_target_data.ted_grant
increase in tgt_grant_alloc() to catch grant counting corruption as
soon as it happened. By default, the detected corruption is
CERROR()-ed, if needed that can be switched to LBUG() using lctl
set_param *.*.lbug_on_grant_miscount.
test-framework.sh:init_param_vars() enables LBUG().

Fixes: af2d3ac30e ("LU-11939 tgt: Do not assert during grant cleanup")
Change-Id: I36ba7496f7b72b4881e98c06ec254a8eefd4c13f
Signed-off-by: Vladimir Saveliev <vlaidimir.saveliev@hpe.com>
Cray-bug-id: LUS-9875
Reviewed-on: https://review.whamcloud.com/42129
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Alexander Boyko <alexander.boyko@hpe.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>