wlcore: add new plt power-mode: CHIP_AWAKE

Under this mode the chip is powered on including sdio
but no FW is downloaded and run, interrupts are not enabled, etc...

This mode is intended to allow RTTT to bridge sdio as a transport
to the chip.

Driver only provides sdio access using the dev_mem debugfs file.

Some fixes done to the code that ensures that PLT mode and normal
driver power mode (ifconfig/add_interface) are mutually excluded.

Signed-off-by: Yair Shapira <yair.shapira@ti.com>
Signed-off-by: Eliad Peller <eliad@wizery.com>
Signed-off-by: Luciano Coelho <luciano.coelho@intel.com>