staging: lustre: o2iblnd: Put back work queue check previously removed

staging: lustre: o2iblnd: Put back work queue check previously removed

The previous patch, http://review.whamcloud.com/21304/, removed
a check needed until LU-5718 is properly addressed.  With
the check, LU-5718 results in an error message and a lost
RDMA operation.  Without it, we have memory corruption and
a crash (much harder to debug).

Putting the check back in case LU-5718 is not fixed soon.

Signed-off-by: Doug Oucharek <doug.s.oucharek@intel.com>
Intel-bug-id: https://jira.hpdd.intel.com/browse/LU-7650
Reviewed-on: http://review.whamcloud.com/22281
Reviewed-by: James Simmons <uja.ornl@yahoo.com>
Reviewed-by: Olaf Weber <olaf@sgi.com>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>
Signed-off-by: James Simmons <jsimmons@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>