Rely on mac80211 airitme utility routines and remove mt76 duplicated code
to estimate tx/rx airtime
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>