rtl8180: adapt for deprecated IEEE80211_CONF_SHORT_SLOT_TIME flag

This updates rtl8180 handling for short slot after "mac80211: fix short
slot handling". Only rtl8180_rtl8225 actually had code for handling
short slot times, so the other RF devices are untouched by this change.

Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/rtl818x/rtl818x.h

@@ -191,6 +191,7 @@ 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 *);
 };
 
 /* Tx/Rx flags are common between RTL818X chips */