ath6kl: rework scheduled scan

This patch reflects changes in the firmware scheduled scan
implementation to behave better in cases with multiple concurrent vifs.
Major changes:

	- scheduled scan filters and state are now programmed per-vif.
	- decouple scheduled scan from host sleep.

To maintain graceful failure with old firmwares, a new firmware
capability bit is introduced: ATH6KL_FW_CAPABILITY_SCHED_SCAN_V2.
ath6kl simply won't advertise scheduled scan to cfg80211 if the
SCHED_SCAN_V2 is not supported.

Since firmwares from here on out won't support the previous implicit API
for scheduled scan (set WoW filters and host sleep), bump the firmware
API to protect old drivers.

Unfortunately, due to firmware RAM constraints ath6kl still cannot
expect a scan complete event at the end of a scheduled scan results
cycle, so the sched_scan_timer is retained.

Signed-off-by: Thomas Pedersen <c_tpeder@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>