ath10k: fix 10.2 fw stats parsing

Both 10.2 firmware binaries 10.2-00082-4 and
10.2.4.20 have introduced ABI changes to fw_stats
each. This caused fw_stats to output wrong data.

Define new structures and use them to parse the
statistics correctly.

Signed-off-by: Michal Kazior <michal.kazior@tieto.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>