ath10k: implement diag data container event

Some firmware revisions may report this event as
part of their diagnostics.

This avoids `unknown event` warnings and adds
tracing for the event.

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