mac80211_hwsim: initialize ieee80211_tx_info at hw_scan_work

In mac80211_hwsim, the probe_req frame is created and sent while
scanning. It is sent with ieee80211_tx_info which is not initialized.
Uninitialized ieee80211_tx_info can cause problems when using
mac80211_hwsim with wmediumd. wmediumd checks the tx_rates field of
ieee80211_tx_info and doesn't relay probe_req frame to other clients
even if it is a broadcasting message.

Call ieee80211_tx_prepare_skb() to initialize ieee80211_tx_info for
the probe_req that is created by hw_scan_work in mac80211_hwsim.

Signed-off-by: JaeMan Park <jaeman@google.com>
Link: https://lore.kernel.org/r/20220113060235.546107-1-jaeman@google.com


[fix memory leak]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>