rtl818x: remove unused conf_erp callback from RF ops struct

The ERP configuration is now done outside RF code in both rtl8180
and rtl8187 drivers.

The conf_erp callback in common RF ops struct is now useless.
Remove it.
Signed-off-by: Andrea Merello <andrea.merello@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/rtl818x/rtl818x.h

@@ -192,7 +192,6 @@ struct rtl818x_rf_ops {
 	void (*init)(struct ieee80211_hw *);
 	void (*stop)(struct ieee80211_hw *);
 	void (*set_chan)(struct ieee80211_hw *, struct ieee80211_conf *);
-	void (*conf_erp)(struct ieee80211_hw *, struct ieee80211_bss_conf *);
 	u8 (*calc_rssi)(u8 agc, u8 sq);
 };