LU-919 obdclass: remove hard coded 0x5a5a5a

LU-919 obdclass: remove hard coded 0x5a5a5a

We assert atomic_t value with hard coded 0x5a5a5a in several places,
which could result in false assertion failure when the reference count
getting very large in some extreme case.

The hard coded 0x5a5a5a should be replaced by LI_POISON.

Signed-off-by: Bruno Faccini <bruno.faccini@bull.net>
Signed-off-by: Niu Yawei <niu@whamcloud.com>
Change-Id: Ia1105e48326c20a37d887ba9dc926ea300d97741
Reviewed-on: http://review.whamcloud.com/1954
Tested-by: Hudson
Tested-by: Maloo <whamcloud.maloo@gmail.com>
Reviewed-by: Johann Lombardi <johann@whamcloud.com>