ath9k: fix double calls to ath_radio_enable

With the enable_radio being uninitialized, ath_radio_enable() might be
called twice, which can leave some hardware in an undefined state.
Signed-off-by: NFelix Fietkau <nbd@openwrt.org>
Cc: stable@kernel.org
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath9k/main.c

@@ -1532,8 +1532,7 @@ static int ath9k_config(struct ieee80211_hw *hw, u32 changed)
 		all_wiphys_idle =  ath9k_all_wiphys_idle(sc);
 		ath9k_set_wiphy_idle(aphy, idle);
 
-		if (!idle && all_wiphys_idle)
-			enable_radio = true;
+		enable_radio = (!idle && all_wiphys_idle);
 
 		/*
 		 * After we unlock here its possible another wiphy