wl1271: Configure QOS nullfunc template for U-APSD

When U-APSD is enabled, device is not sending power save
state notifications to AP using QOS nullfunc frames.

This patch configures nullfunc templates needed for U-APSD.

Signed-off-by: Saravanan Dhanabal <ext-saravanan.dhanabal@nokia.com>
Reviewed-by: Juuso Oikarinen <juuso.oikarinen@nokia.com>
Signed-off-by: Luciano Coelho <luciano.coelho@nokia.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>