mt76: do not use skb_set_queue_mapping for internal purposes

Previously the code used skb_set_queue_mapping for management or non-bufferable
powersave frames that need to be sent to a different hardware queue.
This can confuse AQL, which expects the value to remain the same until the tx
status report.
The only place that currently uses the altered skb queue mapping is the txwi
write function. Change the code to pass the hardware queue id as a function
parameter instead.

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