mac80211: Remove redundent assignment channel_type

Fix the following coccicheck warnings:

net/mac80211/util.c:3265:3: warning: Value stored to 'channel_type' is
never read [clang-analyzer-deadcode.DeadStores].
Reported-by: Abaci Robot <abaci@linux.alibaba.com>
Signed-off-by: Jiapeng Chong <jiapeng.chong@linux.alibaba.com>
Link: https://lore.kernel.org/r/20220113161557.129427-1-jiapeng.chong@linux.alibaba.comSigned-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/util.c

@@ -3279,7 +3279,6 @@ bool ieee80211_chandef_ht_oper(const struct ieee80211_ht_operation *ht_oper,
 		channel_type = NL80211_CHAN_HT40MINUS;
 		break;
 	default:
-		channel_type = NL80211_CHAN_NO_HT;
 		return false;
 	}