RDMA/bnxt_re: Avoid accessing nq->bar_reg_iomem in failure case

RDMA/bnxt_re: Avoid accessing nq->bar_reg_iomem in failure case

In the failure path, nq->bar_reg_iomem gets accessed without
initializing. Avoid this by calling the bnxt_qplib_nq_stop_irq only if the
initialization is complete.

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Fixes: 3ce80b7901f8 ("RDMA/bnxt_re: Add bnxt_re RoCE driver")
Fixes: fb06cca65ebd ("RDMA/bnxt_re: Fix broken RoCE driver due to recent L2 driver changes")
Signed-off-by: Selvin Xavier <selvin.xavier@broadcom.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>