SUNRPC: Revert cc93ce95 ("svcrdma: Retain the page backing rq_res.head[0].iov_base")

Pre-requisite for releasing pages in the send completion handler.
Reverted by hand: patch -R would not apply cleanly.
Reviewed-by: Jeff Layton <jlayton@kernel.org>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>

net/sunrpc/xprtrdma/svc_rdma_sendto.c

@@ -975,11 +975,6 @@ int svc_rdma_sendto(struct svc_rqst *rqstp)
 	ret = svc_rdma_send_reply_msg(rdma, sctxt, rctxt, rqstp);
 	if (ret < 0)
 		goto put_ctxt;
-
-	/* Prevent svc_xprt_release() from releasing the page backing
-	 * rq_res.head[0].iov_base. It's no longer being accessed by
-	 * the I/O device. */
-	rqstp->rq_respages++;
 	return 0;
 
 reply_chunk: