wifi: mt76: only mark tx-status-failed frames as ACKed on mt76x0/2

The interrupt status polling is unreliable, which can cause status events
to get lost. On all newer chips, txs-timeout is an indication that the
packet was either never sent, or never acked.
Fixes issues with inactivity polling.

Link: https://patch.msgid.link/20250311103646.43346-6-nbd@nbd.name


Signed-off-by: Felix Fietkau <nbd@nbd.name>