gianfar: Restore promisc mode on gfar_init_mac()

Reactivate promiscuous mode in H/W upon gfar_init_mac(), if the
net dev requires it (IFF_PROMISC flag set).
This way the promisc mode is preserved accross device reset conditions
like tx timeout, device restore, a.s.o.

Signed-off-by: Voncken C Acksys <cedric.voncken@acksys.fr>
Signed-off-by: Claudiu Manoil <claudiu.manoil@freescale.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/freescale/gianfar.c

@@ -355,6 +355,10 @@ static void gfar_init_mac(struct net_device *ndev)
 		gfar_write(&regs->rir0, DEFAULT_RIR0);
 	}
 
+	/* Restore PROMISC mode */
+	if (ndev->flags & IFF_PROMISC)
+		rctrl |= RCTRL_PROM;
+
 	if (ndev->features & NETIF_F_RXCSUM)
 		rctrl |= RCTRL_CHECKSUMMING;