LU-12495 obdclass: qos penalties miscalculated

In lqos_calc_penalties(), the penalty_per_obj is miscalculated.

Also improve sanity test_413b: take both blocks and inodes into
account to make the test more robost.

Fixes: d3090bb ("LU-11213 lod: share object alloc QoS code with LMV")
Signed-off-by: Lai Siyao <lai.siyao@whamcloud.com>
Change-Id: Ie965fc3bfa3e303c27f93a6e1a428cc4a90f8548
Reviewed-on: https://review.whamcloud.com/36269
Tested-by: jenkins <devops@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Hongchao Zhang <hongchao@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>