mac80211: use Probe Request template when sending a direct scan

As mac80211 now has a separate function for creating Probe Request templates,
better to use it when sending direct Probe Requests to an AP. Only the
bssid needs to be updated in the template before sending it.

Signed-off-by: Kalle Valo <kalle.valo@nokia.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>