We should preserve the original "status" error code instead of resetting
it to zero.  Returning ERR_PTR(0) is the same as NULL and results in a
NULL dereference in the callers.  I added a printk() on error instead.

Fixes: 45e86b33 ("RDMA/ocrdma: Cache recv DB until QP moved to RTR")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>