Initialize sis_ring_init() 'sis_rx_prod' and 'sis_rx_cons' to 0

[Kevin Lo]

ok?

Index: sys/dev/pci/if_sis.c
===================================================================
RCS file: /cvs/src/sys/dev/pci/if_sis.c,v
retrieving revision 1.137
diff -u -p -u -p -r1.137 if_sis.c
--- sys/dev/pci/if_sis.c        10 Jul 2020 13:26:38 -0000      1.137
+++ sys/dev/pci/if_sis.c        15 Jul 2020 07:11:47 -0000
@@ -1285,7 +1285,7 @@ sis_ring_init(struct sis_softc *sc)
                ld->sis_rx_list[i].sis_ctl = 0;
        }
 
-       cd->sis_rx_prod = cd->sis_rx_cons;
+       cd->sis_rx_prod = cd->sis_rx_cons = 0;
        if_rxr_init(&cd->sis_rx_ring, 2, SIS_RX_LIST_CNT - 1);
        sis_fill_rx_ring(sc);