xprtrdma: Initialize rb_credits in one place

Clean up/code de-duplication.

Nit: RPC_CWNDSHIFT is incorrect as the initial value for xprt->cwnd.
This mistake does not appear to have operational consequences, since
the cwnd value is replaced with a valid value upon the first Receive
completion.

Signed-off-by: Chuck Lever <chuck.lever@oracle.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
diff --git a/net/sunrpc/xprtrdma/verbs.c b/net/sunrpc/xprtrdma/verbs.c
index f4b1365..97bc15e 100644
--- a/net/sunrpc/xprtrdma/verbs.c
+++ b/net/sunrpc/xprtrdma/verbs.c
@@ -727,6 +727,7 @@ rpcrdma_ep_connect(struct rpcrdma_ep *ep, struct rpcrdma_ia *ia)
 	ep->rep_connected = 0;
 	xprt_clear_connected(xprt);
 
+	rpcrdma_reset_cwnd(r_xprt);
 	rpcrdma_post_recvs(r_xprt, true);
 
 	rc = rdma_connect(ia->ri_id, &ep->rep_remote_cma);
@@ -1163,7 +1164,6 @@ int rpcrdma_buffer_create(struct rpcrdma_xprt *r_xprt)
 		list_add(&req->rl_list, &buf->rb_send_bufs);
 	}
 
-	buf->rb_credits = 1;
 	init_llist_head(&buf->rb_free_reps);
 
 	rc = rpcrdma_sendctxs_create(r_xprt);