xprtrdma: Initialize re_id before removal registration

Summary

In the Linux kernel, the following vulnerability has been resolved: xprtrdma: Initialize re_id before removal registration rpcrdma_create_id() registers ep->re_rn with the rpcrdma ib_client before returning the new rdma_cm_id to rpcrdma_ep_create(). However rpcrdma_ep_create() currently stores that pointer in ep->re_id only after rpcrdma_create_id() returns. A local administrator can race an NFS/RDMA mount against RDMA device removal. If rpcrdma_remove_one() observes the just-registered notification before rpcrdma_ep_create() assigns ep->re_id, rpcrdma_ep_removal_done() calls trace_xprtrdma_device_removal(NULL). The tracepoint dereferences id->device->name and copies id->route.addr.dst_addr, so the callback can crash the kernel with a NULL pointer dereference. Store the rdma_cm_id in ep->re_id immediately before publishing ep->re_rn. The existing error path still destroys the id directly if registration fails; ep is then freed by the caller without using ep->re_id. Remove the later duplicate assignment in rpcrdma_ep_create().