wl12xx: add config_hangover command

Add wl12xx_acx_config_hangover() and respective conf values.
This command configures how long the chip will stay awake
after it was configured to enter psm.

Signed-off-by: Eliad Peller <eliad@wizery.com>
Signed-off-by: Luciano Coelho <coelho@ti.com>