ath6kl: Move ath6kl_cfg80211_stop() call specific to deep sleep and cut pwr

ath6kl_cfg80211_stop() call is not applicable for WOW mode. Hence moving
this call to deep sleep and cut pwr specific cases.

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