ath9k: use consistent value for REDUCE_SCALED_POWER_BY_THREE_CHAIN

The REDUCE_SCALED_POWER_BY_THREE_CHAIN symbol is
defined in different eeprom files, and the value
varies between the different files.

In eeprom_def.c and in ar9003_eeprom.c the value
of the symbol is 9, however the comments in these
files indicates the value should be 10*log10(3)*2
which is 9.54242509439325. Replace the the value
to 10 in these files.

Also add comments to eeprom_9287.c.
Signed-off-by: Gabor Juhos <juhosg@openwrt.org>
Signed-off-by: John W. Linville <linville@tuxdriver.com>

drivers/net/wireless/ath/ath9k/ar9003_eeprom.c

@@ -31,7 +31,7 @@
 #define CTL_11G_EXT (CTL_11G | EXT_ADDITIVE)
 #define CTL_11B_EXT (CTL_11B | EXT_ADDITIVE)
 #define REDUCE_SCALED_POWER_BY_TWO_CHAIN     6  /* 10*log10(2)*2 */
-#define REDUCE_SCALED_POWER_BY_THREE_CHAIN   9  /* 10*log10(3)*2 */
+#define REDUCE_SCALED_POWER_BY_THREE_CHAIN   10 /* 10*log10(3)*2 */
 #define PWRINCR_3_TO_1_CHAIN      9             /* 10*log(3)*2 */
 #define PWRINCR_3_TO_2_CHAIN      3             /* floor(10*log(3/2)*2) */
 #define PWRINCR_2_TO_1_CHAIN      6             /* 10*log(2)*2 */

drivers/net/wireless/ath/ath9k/eeprom_9287.c

@@ -564,8 +564,8 @@ static void ath9k_hw_set_ar9287_power_per_rate_table(struct ath_hw *ah,
 	(((cfgCtl & ~CTL_MODE_M) | (pCtlMode[ctlMode] & CTL_MODE_M)) == \
 	 ((pEepData->ctlIndex[i] & CTL_MODE_M) | SD_NO_CTL))
 
-#define REDUCE_SCALED_POWER_BY_TWO_CHAIN     6
-#define REDUCE_SCALED_POWER_BY_THREE_CHAIN   10
+#define REDUCE_SCALED_POWER_BY_TWO_CHAIN     6  /* 10*log10(2)*2 */
+#define REDUCE_SCALED_POWER_BY_THREE_CHAIN   10 /* 10*log10(3)*2 */
 
 	u16 twiceMaxEdgePower;
 	int i;

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

@@ -992,7 +992,7 @@ static void ath9k_hw_set_def_power_per_rate_table(struct ath_hw *ah,
 						  u16 powerLimit)
 {
 #define REDUCE_SCALED_POWER_BY_TWO_CHAIN     6  /* 10*log10(2)*2 */
-#define REDUCE_SCALED_POWER_BY_THREE_CHAIN   9 /* 10*log10(3)*2 */
+#define REDUCE_SCALED_POWER_BY_THREE_CHAIN   10 /* 10*log10(3)*2 */
 
 	struct ar5416_eeprom_def *pEepData = &ah->eeprom.def;
 	u16 twiceMaxEdgePower;