ath10k: defer hw setup to start/stop mac80211 hooks

This fixes suspend-to-disk. The hardware is now
re-initialized upon freeze/thaw properly.

This also makes suspend/resume re-initialize the
hardware as WoWLAN support is not done yet.

With some little work it should be possible to
support hw reconfiguration for hw/fw recovery.

HW must be initialized once before registering to
mac80211 because FW determinates what hw
capabilities can be advertised.

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