RDMA/cm: Fix access to uninitialized variable

The ndev will be initialized and held only for successful
ib_get_cached_gid(), otherwise it is garbage stack memory.
Calling dev_put() in failure path is wrong.

Fixes: 16c72e40 ("IB/cm: Refactor to avoid setting path record software only fields")
Signed-off-by: Parav Pandit <parav@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Reviewed-by: Yuval Shaia <yuval.shaia@oracle.com>
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>

drivers/infiniband/core/cm.c

@@ -1901,8 +1901,6 @@ static int cm_req_handler(struct cm_work *work)
 				grh->sgid_index,
 				&gid, &gid_attr);
 	if (ret) {
-		if (gid_attr.ndev)
-			dev_put(gid_attr.ndev);
 		ib_send_cm_rej(cm_id, IB_CM_REJ_UNSUPPORTED, NULL, 0, NULL, 0);
 		goto rejected;
 	}