ath9k: Fix regression in PA calibration

The commit "ath9k: Fix bugs in programming registers during PA CAL"
removed a REG_READ of 0x7834. This resulted in incorrect
computation of the subsequent value to be written in RF2G6.

This patch fixes the regression by re-adding the REG_READ.
Signed-off-by: NSujith <Sujith.Manoharan@atheros.com>
Signed-off-by: NJohn W. Linville <linville@tuxdriver.com>

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

@@ -936,6 +936,7 @@ static inline void ath9k_hw_9285_pa_cal(struct ath_hw *ah, bool is_reset)
 		regVal |= (1 << (19 + i));
 		REG_WRITE(ah, 0x7834, regVal);
 		udelay(1);
+		regVal = REG_READ(ah, 0x7834);
 		regVal &= (~(0x1 << (19 + i)));
 		reg_field = MS(REG_READ(ah, 0x7840), AR9285_AN_RXTXBB1_SPARE9);
 		regVal |= (reg_field << (19 + i));