RDMA/bnxt_re: Fix an error code in bnxt_qplib_create_srq()

We should return -ENOMEM if the allocation fails.  (The current code
returns succees).

Fixes: 37cb11ac ("RDMA/bnxt_re: Add SRQ support for Broadcom adapters")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Acked-By: Devesh Sharma <devesh.sharma@broadcom.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>