xprtrdma: rpcrdma_mr_pop() already does list_del_init()

The rpcrdma_mr_pop() earlier in the function has already cleared
out mr_list, so it must not be done again in the error path.

Fixes: 8475689 ("xprtrdma: Remove fr_state")
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>

net/sunrpc/xprtrdma/frwr_ops.c

@@ -576,7 +576,6 @@ void frwr_unmap_sync(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req)
 		mr = container_of(frwr, struct rpcrdma_mr, frwr);
 		bad_wr = bad_wr->next;
 
-		list_del_init(&mr->mr_list);
 		frwr_mr_recycle(mr);
 	}
 }