drivers/net: const-ify ethtool_ops declarations

Signed-off-by: Jeff Garzik <jeff@garzik.org>

drivers/net/wireless/hostap/hostap.h

@@ -86,7 +86,7 @@ void hostap_info_process(local_info_t *local, struct sk_buff *skb);
 /* hostap_ioctl.c */
 
 extern const struct iw_handler_def hostap_iw_handler_def;
-extern struct ethtool_ops prism2_ethtool_ops;
+extern const struct ethtool_ops prism2_ethtool_ops;
 
 int hostap_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd);