ath6kl: cut power during suspend

If sdio controller doesn't support keep power, cut power from hardware
during suspend and restart firmware during resume. If we are connected
during suspend, send a disconnected event to user space.

Earlier suspend failed with an error if sdio didn't support keep power.
Now suspend will happen succesfully even with that case.

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