Louis reported that a static checker was complaining that
the 'dst' variable was set (multiple times) but not used.
This is due to a previous commit having removed the usage
(apparently erroneously), so add it back.

Fixes: a344d677 ("mac80211: allow drivers to support NL80211_SCAN_FLAG_RANDOM_ADDR")
Reported-by: Louis Langholtz <lou_langholtz@me.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>