nl80211: Update the assoc_freq during connect

nl80211: Update the assoc_freq during connect

drv->assoc_freq was not updated during the connect command (neither
during the command's invocation nor after getting the event) unlike with
auth/assoc case where assoc_freq is updated. This resulted in
nl80211_get_link_noise() (and any other function for that matter) using
the improper drv->assoc_freq value with drivers that use the connect
API. Fix this by updating drv->assoc_freq on connect command and when
fetching the frequency from the driver.

Signed-hostap: Jouni Malinen <jouni@qca.qualcomm.com>