wl1271: Configure probe-request template when associated

Configure a probe-request template to the wl1271 when associated - the
wl1271 will use this to attempt to recover a connection when beacon loss
is detected.

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>