mac802154: rework open count

Some cleanup to avoid pre- and post-calculation with the open_count
variable.
mac802154: remove ieee802154_addr from driver_ops

This function is never used by any driver. There exist also no comment
for this. In my opinion it was a try to implement hardware address
filter but we have already such driver ops for this functionallity.
mac802154: rework sdata state change to running

This patch reworks the handling for setting the state like mac80211. We
use bit's instead a bool variable. The mutex is not needed because it's
locked by rtnl lock.