ath9k_hw: remove ATH9K_CAP_TXPOW

replace calls that read this capability with accesses to ath9k_hw's
regulatory data.

Signed-off-by: Felix Fietkau <nbd@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/ath9k/main.c b/drivers/net/wireless/ath/ath9k/main.c
index f38da29..c8de50f 100644
--- a/drivers/net/wireless/ath/ath9k/main.c
+++ b/drivers/net/wireless/ath/ath9k/main.c
@@ -51,13 +51,11 @@
 static void ath_update_txpow(struct ath_softc *sc)
 {
 	struct ath_hw *ah = sc->sc_ah;
-	u32 txpow;
 
 	if (sc->curtxpow != sc->config.txpowlimit) {
 		ath9k_hw_set_txpowerlimit(ah, sc->config.txpowlimit);
 		/* read back in case value is clamped */
-		ath9k_hw_getcapability(ah, ATH9K_CAP_TXPOW, 1, &txpow);
-		sc->curtxpow = txpow;
+		sc->curtxpow = ath9k_hw_regulatory(ah)->power_limit;
 	}
 }