ath9k_hw: make spur mitigation a callback

This only differs between single-chip solutions and non single-chip
solutions.

Signed-off-by: Luis R. Rodriguez <lrodriguez@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath9k/hw.h

@@ -550,6 +550,11 @@ struct ath_hw {
 
 	/* Callback for radio frequency change */
 	int (*ath9k_hw_rf_set_freq)(struct ath_hw *ah, struct ath9k_channel *chan);
+
+	/* Callback for baseband spur frequency */
+	void (*ath9k_hw_spur_mitigate_freq)(struct ath_hw *ah,
+					    struct ath9k_channel *chan);
+
 	/* Used to program the radio on non single-chip devices */
 	u32 *analogBank0Data;
 	u32 *analogBank1Data;