RDMA/qedr: Missing error code in qedr_init_user_queue()

We should return -ENOMEM if the kzalloc() fails.  We currently return
success.

Fixes: 69ad0e7f ("RDMA/qedr: Add support for iWARP in user space")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>