net: remove unnecessary return's

One of my pet coding style peeves is the practice of
adding extra return; at the end of function.
Kill several instances of this in network code.

I suppose some coccinelle wizardy could do this automatically.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/wireless/chan.c

@@ -701,6 +701,4 @@ cfg80211_get_chan_state(struct wireless_dev *wdev,
 	case NUM_NL80211_IFTYPES:
 		WARN_ON(1);
 	}
-
-	return;
 }