wl1271: Reduce PSM entry hang over period from 128 => 1 ms

Currently, we configure a 128ms hang over period for the PSM entry
(the firmware will remain active for 128ms after sending the null func for
PSM and getting an ack for it.) This is a huge power consumption issue, and
appears unnecessary. So, configure the value to 1 ms.

Signed-off-by: Juuso Oikarinen <juuso.oikarinen@nokia.com>
Reviewed-by: Janne Ylalehto <janne.ylalehto@nokia.com>
Signed-off-by: Luciano Coelho <luciano.coelho@nokia.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>