staging: vt6655: mac80211 conversion: enable power saving

Convert PSvEnablePowerSaving and PSvEnablePowerSaving

Remove mgmt->wCurrAID and use pDevice->current_aid

We nolonger send the PSbSendNullPacket.

Signed-off-by: Malcolm Priestley <tvboxspy@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>