LU-9679 obdclass: use OBD_ALLOC_PTR_ARRAY() and others

LU-9679 obdclass: use OBD_ALLOC_PTR_ARRAY() and others

Use:
  OBD_ALLOC_PTR_ARRAY
  OBD_ALLOC_PTR_ARRAY_WAIT
  OBD_FREE_PTR_ARRAY
  OBD_ALLOC_PTR_ARRAY_LARGE
  OBD_FREE_PTR_ARRAY_LARGE

for allocating and freeing arrays in obdclass

Signed-off-by: Mr NeilBrown <neilb@suse.de>
Change-Id: I2ebf853769a9711f1f99431aa7f69a18ba2ea552
Reviewed-on: https://review.whamcloud.com/38121
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Shaun Tancheff <shaun.tancheff@hpe.com>
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>