[atv] fixed bitmask setting for multicast mode

This wrong setting always overwrote the flag for promiscouos mode.
It also did not revoke the flag for multicast mode, it was always set.
[atv] again wrong bit operations...

... inside net net-driver.
Merge pull request #6 from at-visions/network-patch

[atv] fixed bitmask setting for multicast mode
Merge remote-tracking branch 'pivosgroup/master' into dev/HD18M