wifi: rtl8xxxu: rtl8xxxu_rx_complete(): remove unnecessary return

Remove a return statement at the end of a void function.

This fixes a checkpatch warning.

WARNING: void function return statements are not generally useful
6206: FILE: ./drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c:6206:
+  return;
+}
Signed-off-by: Martin Kaiser <martin@kaiser.cx>
Reviewed-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20230427185936.923777-1-martin@kaiser.cx

drivers/net/wireless/realtek/rtl8xxxu/rtl8xxxu_core.c

@@ -6443,7 +6443,6 @@ static void rtl8xxxu_rx_complete(struct urb *urb)
 cleanup:
 	usb_free_urb(urb);
 	dev_kfree_skb(skb);
-	return;
 }
 
 static int rtl8xxxu_submit_rx_urb(struct rtl8xxxu_priv *priv,