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: Sujith <Sujith.Manoharan@atheros.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/drivers/net/wireless/ath/ath9k/calib.c b/drivers/net/wireless/ath/ath9k/calib.c
index 22a3a69..0ad6d0b 100644
--- a/drivers/net/wireless/ath/ath9k/calib.c
+++ b/drivers/net/wireless/ath/ath9k/calib.c
@@ -936,6 +936,7 @@
 		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));