mac80211: initialize return flags in HE 6 GHz operation parsing

Dan points out that if ieee80211_chandef_he_6ghz_oper() succeeds,
we don't initialize 'ret'. Initialize it to 0 in this case, since
everything went fine and nothing has to be disabled.

Reported-by: Dan Carpenter <[e-mail]>
Fixes: 57fa5e85d53c ("mac80211: determine chandef from HE 6 GHz operation")
Signed-off-by: Johannes Berg <[e-mail]>
Link: https://lore.kernel.org/r/20200603111500.bd2a5ff37b83.I2c3f338ce343b581db493eb9a0d988d1b626c8fb@changeid
Signed-off-by: Johannes Berg <[e-mail]>

net/mac80211/mlme.c

···
 			ret = IEEE80211_STA_DISABLE_HT |
 			      IEEE80211_STA_DISABLE_VHT |
 			      IEEE80211_STA_DISABLE_HE;
+		else
+			ret = 0;
 		vht_chandef = *chandef;
 		goto out;
 	}