wl1271: Remove excess null-data template settings

The null-data template (nullfunc) is dependent on the BSSID of the
current AP only, so it needs to be updated only when the BSSID changes.

Removed excess setting of the template.

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