ath10k: fix some pci wake/sleep issues

In some cases the device ends up sleeping while
ath10k didn't expect it to leading to reading
garbage from registers, e.g. when shared irqs are
used and the driver is in powered down state.

This effectively makes the device remain awake all
the time even when all interfaces are down.

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