r8169: respect userspace disabling IFF_MULTICAST

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>