rt2x00: fix TX_PWR_CFG_4 register definition

Some of the macros used to describe the TX_PWR_CFG_4 register accidentally
refer to TX_PWR_CFG_3, probably a copy&paste error. Fix that.
Signed-off-by: NDaniel Golle <daniel@makrotopia.org>
Acked-by: NStanislaw Gruszka <sgruszka@redhat.com>
Signed-off-by: NKalle Valo <kvalo@codeaurora.org>

drivers/net/wireless/ralink/rt2x00/rt2800.h

@@ -1171,10 +1171,10 @@
 #define TX_PWR_CFG_4_UKNOWN7		FIELD32(0x00000f00)
 #define TX_PWR_CFG_4_UKNOWN8		FIELD32(0x0000f000)
 /* bits for 3T devices */
-#define TX_PWR_CFG_3_STBC4_CH0		FIELD32(0x0000000f)
-#define TX_PWR_CFG_3_STBC4_CH1		FIELD32(0x000000f0)
-#define TX_PWR_CFG_3_STBC6_CH0		FIELD32(0x00000f00)
-#define TX_PWR_CFG_3_STBC6_CH1		FIELD32(0x0000f000)
+#define TX_PWR_CFG_4_STBC4_CH0		FIELD32(0x0000000f)
+#define TX_PWR_CFG_4_STBC4_CH1		FIELD32(0x000000f0)
+#define TX_PWR_CFG_4_STBC6_CH0		FIELD32(0x00000f00)
+#define TX_PWR_CFG_4_STBC6_CH1		FIELD32(0x0000f000)
 
 /*
  * TX_PIN_CFG: