ath6kl: configure wow filters per-vif

Only WoW filters for the first vif were being set, causing failures to
wake up on any concurrent connected vifs. Handle all per-vif suspend
and resume tasks.

Since cfg80211 issues user wow filters on a per-wiphy basis, set any
custom filters on all connected vifs.

Starting WoW in firmware and setting host sleep mode is still handled on
a global per-phy level. The first vif is always used for bookkeeping
regardless of whether it is connected or not.

WoW is cancelled if no connected vifs are found.

No firmware capability bits or API bump is needed for this patch, as
setting filters for vifs with index > 0 will simply overwrite the index
0 filters in the current implementation. While not correct, this is
identical to the existing behavior.

kvalo: fix a checkpatch warning in ath6kl_wow_resume()

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