tg3: Fix 5717 serdes powerdown problem

If port 0 of a 5717 serdes device powers down, it hides the phy from
port 1.  This patch works around the problem by keeping port 0's phy
powered up.
Signed-off-by: NMatt Carlson <mcarlson@broadcom.com>
Signed-off-by: NMichael Chan <mchan@broadcom.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/tg3.c

@@ -2779,7 +2779,9 @@ static void tg3_power_down_phy(struct tg3 *tp, bool do_low_power)
 	if (GET_ASIC_REV(tp->pci_chip_rev_id) == ASIC_REV_5700 ||
 	    GET_ASIC_REV(tp->pci_chip_rev_id) == ASIC_REV_5704 ||
 	    (GET_ASIC_REV(tp->pci_chip_rev_id) == ASIC_REV_5780 &&
-	     (tp->phy_flags & TG3_PHYFLG_MII_SERDES)))
+	     (tp->phy_flags & TG3_PHYFLG_MII_SERDES)) ||
+	    (GET_ASIC_REV(tp->pci_chip_rev_id) == ASIC_REV_5717 &&
+	     !tp->pci_fn))
 		return;
 
 	if (GET_CHIP_REV(tp->pci_chip_rev_id) == CHIPREV_5784_AX ||