cpu/nrf52/radio/nrf802154: fix beacon acceptance · RIOT-OS/RIOT@ea0c0ee

Commit message is longer than 50 (but < 72) characters: "cpu/nrf52/radio/nrf802154: fix beacon frame acceptance in _l2filter"

Commit message is longer than 50 (but < 72) characters: "fixup! fixup! tests/drivers/nrf802154: test if Beacons can be received"

Commit message is longer than 50 (but < 72) characters: "fixup! tests/drivers/nrf802154: test if Beacons can be received"