ath10k: simplify pktlog htt event processing

It is expected that all pktlog events for 10.4 firmware based solutions
should come through CE8 where as in case of 10.2 firmware based solutions,
it should come through one of the HTT events (HTT_T2H_MSG_TYPE_PKTLOG).

But from experiments with 10.4 based solutions, it is observed that pktlog
event for ATH_PKTLOG_TYPE_TX_MSDU_ID is coming through HTT pktlog event.
Currently, we always parse with 10.2 pktlog header which will lead to
pktlog decoding issues (payload length mismatch exceptions)

For trace points, it is required to provide only the payload size. So
fixing this by simplifying the payload size calculation without the use of
ath10k pktlog headers.

While there, remove the unused ath10k pktlog headers.

Signed-off-by: Ashok Raj Nagarajan <arnagara@qti.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>