fix.diff — DF-4267: restore correct RX ring wrap-around in wb_list_rx_init().

The DragonFly port collapsed FreeBSD's if/else wrap-around into a ternary and
dropped the "i ==" comparison, making the condition the constant 63:
nexti is always 0, so every RX descriptor (software wb_nextdesc and hardware
wb_next) links to descriptor 0 — a 1-deep self-ring instead of a closed
64-descriptor ring.

Applies on top of sys/dev/netif/wb/if_wb.c (read-only audit tree; never applied).

--- a/sys/dev/netif/wb/if_wb.c
+++ b/sys/dev/netif/wb/if_wb.c
@@ -906,7 +906,7 @@ wb_list_rx_init(struct wb_softc *sc)
 		cd->wb_rx_chain[i].wb_buf = &ld->wb_rxbufs[i];
 		if (wb_newbuf(sc, &cd->wb_rx_chain[i], NULL) == ENOBUFS)
 			return(ENOBUFS);
-		nexti = (WB_RX_LIST_CNT - 1) ? 0 : i + 1;
+		nexti = (i == WB_RX_LIST_CNT - 1) ? 0 : i + 1;
 		cd->wb_rx_chain[i].wb_nextdesc = &cd->wb_rx_chain[nexti];
 		ld->wb_rx_list[i].wb_next =  vtophys(&ld->wb_rx_list[nexti]);
 	}