NTB: perf: Don't require one more memory window than number of peers

ntb_perf should not require more than one memory window per peer. This
was probably an off-by-one error.

Fixes: 5648e56d ("NTB: ntb_perf: Add full multi-port NTB API support")
Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Acked-by: Allen Hubbe <allenbh@gmail.com>
Tested-by: Alexander Fomichev <fomichev.ru@gmail.com>
Signed-off-by: Jon Mason <jdmason@kudzu.us>

drivers/ntb/test/ntb_perf.c

@@ -654,7 +654,7 @@ static int perf_init_service(struct perf_ctx *perf)
 {
 	u64 mask;
 
-	if (ntb_peer_mw_count(perf->ntb) < perf->pcnt + 1) {
+	if (ntb_peer_mw_count(perf->ntb) < perf->pcnt) {
 		dev_err(&perf->ntb->dev, "Not enough memory windows\n");
 		return -EINVAL;
 	}