ath10k: enable pci soc powersaving

By using SOC_WAKE register it is possible to bring
down power consumption of QCA61X4 from 36mA to
16mA when associated and idle.

Currently the sleep threshold/grace period is at a
very conservative value of 60ms.

Contrary to QCA61X4 the QCA988X firmware doesn't
have Rx/beacon filtering available for client mode
and SWBA events are used for beaconing in AP/IBSS
so the SoC needs to be woken up at least every
~100ms in most cases. This means that QCA988X
is at a disadvantage and the power consumption
won't drop as much as for QCA61X4.

Due to putting irq-safe spinlocks on every MMIO
read/write it is expected this can cause a little
performance regression on some systems. I haven't
done any thorough measurements but some of my
tests don't show any extreme degradation.

The patch removes some explicit pci_wake calls
that were added in 320e14b8db51aa ("ath10k: fix
some pci wake/sleep issues"). This is safe because
all MMIO accesses are now wrapped and the device
is woken up automatically if necessary.

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