cfg80211: initialize on-stack chandefs

In a few places we don't properly initialize on-stack chandefs,
resulting in EDMG data to be non-zero, which broke things.

Additionally, in a few places we rely on the driver to init the
data completely, but perhaps we shouldn't as non-EDMG drivers
may not initialize the EDMG data, also initialize it there.

Cc: stable@vger.kernel.org
Fixes: 2a38075cd0be ("nl80211: Add support for EDMG channels")
Reported-by: Dmitry Osipenko <digetx@gmail.com>
Tested-by: Dmitry Osipenko <digetx@gmail.com>
Link: https://lore.kernel.org/r/1569239475-I2dcce394ecf873376c386a78f31c2ec8b538fa25@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
diff --git a/net/wireless/wext-compat.c b/net/wireless/wext-compat.c
index 7b6529d..cac9e28 100644
--- a/net/wireless/wext-compat.c
+++ b/net/wireless/wext-compat.c
@@ -798,7 +798,7 @@ static int cfg80211_wext_giwfreq(struct net_device *dev,
 {
 	struct wireless_dev *wdev = dev->ieee80211_ptr;
 	struct cfg80211_registered_device *rdev = wiphy_to_rdev(wdev->wiphy);
-	struct cfg80211_chan_def chandef;
+	struct cfg80211_chan_def chandef = {};
 	int ret;
 
 	switch (wdev->iftype) {