mac80211: fix error handling in ieee80211_register_hw()

Fix to return a negative error code -ENOMEM from the kmemdup
error handling case instead of 0.

Fixes: 09b4a4fa ("mac80211: introduce capability flags for VHT EXT NSS support")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>

net/mac80211/main.c

@@ -1203,8 +1203,10 @@ int ieee80211_register_hw(struct ieee80211_hw *hw)
 			continue;
 
 		sband = kmemdup(sband, sizeof(*sband), GFP_KERNEL);
-		if (!sband)
+		if (!sband) {
+			result = -ENOMEM;
 			goto fail_rate;
+		}
 
 		wiphy_dbg(hw->wiphy, "copying sband (band %d) due to VHT EXT NSS BW flag\n",
 			  band);