ath10k: use scan burst for hw roc

This improves chances of getting onto a foreign
channel and thus makes P2P a bit more reliable.

Without scan burst it was possible for firmware to
not switch to foreign channel resulting in "failed
to switch to channel for roc scan" warning. This
would also effectively fail some offchan tx
requests and lead to P2P find/connect taking
longer. This could be observed when other vifs
were running/busy, e.g. with P2P GO.

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