wl12xx: wakeup chip from ELP during scan

Commands are sometimes sent to FW on scan completion. Make sure the chip
is awake to receive them. Sending commands while the chip is in ELP
can cause SDIO read errors and/or crash the FW.

Signed-off-by: Arik Nemtsov <arik@wizery.com>
Signed-off-by: Ido Yariv <ido@wizery.com>
Signed-off-by: Luciano Coelho <coelho@ti.com>