Fix to return error code -ENOMEM from the rdma_zalloc_drv_obj() error
handling case instead of 0, as done elsewhere in this function.

Fixes: e8ac9389 ("RDMA: Fix allocation failure on pointer pd")
Fixes: 21a428a0 ("RDMA: Handle PD allocations by IB/core")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Reviewed-by: Leon Romanovsky <leonro@mellanox.com>
Link: https://lore.kernel.org/r/20190801012725.150493-1-weiyongjun1@huawei.comSigned-off-by: Doug Ledford <dledford@redhat.com>