r8169: respect userspace disabling IFF_MULTICAST

So far we ignore the setting of IFF_MULTICAST. Fix this and clear bit
AcceptMulticast if IFF_MULTICAST isn't set.

Note: Based on the implementations I've seen it doesn't seem to be 100% clear
what a driver is supposed to do if IFF_ALLMULTI is set but IFF_MULTICAST
is not. This patch is based on the understanding that IFF_MULTICAST has
precedence.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Heiner Kallweit <hkallweit1@gmail.com>
Link: https://lore.kernel.org/r/4a57ba02-d52d-4369-9f14-3565e6c1f7dc@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

Author: hkallweit

drivers/net/ethernet/realtek/r8169_main.c

@@ -2582,6 +2582,8 @@ static void rtl_set_rx_mode(struct net_device *dev)
 
 	if (dev->flags & IFF_PROMISC) {
 		rx_mode |= AcceptAllPhys;
+	} else if (!(dev->flags & IFF_MULTICAST)) {
+		rx_mode &= ~AcceptMulticast;
 	} else if (netdev_mc_count(dev) > MC_FILTER_LIMIT ||
 		   dev->flags & IFF_ALLMULTI ||
 		   tp->mac_version == RTL_GIGA_MAC_VER_35 ||