ath9k: Check MCI PowerSave state

The power save state of MCI has to be disabled
when enabling WoW sleep, check this properly.
ar9003_mci_state() doesn't handle MCI_STATE_GET_WLAN_PS_STATE
right now, but this will be done later when proper
support for MCI/PS is added.

Signed-off-by: Sujith Manoharan <c_manoha@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>