wifi: rt2x00: add TX LOFT calibration for MT7620

Add TX LOFT calibration from mtk driver.
Signed-off-by: Tomislav Požega <pozega.tomislav@gmail.com>
Signed-off-by: Daniel Golle <daniel@makrotopia.org>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/d9295a9138a1f552b648aacb84e1419d38f5c896.1663445157.git.daniel@makrotopia.org

drivers/net/wireless/ralink/rt2x00/rt2800lib.h

@@ -17,6 +17,16 @@
 #define WCID_START	33
 #define WCID_END	222
 #define STA_IDS_SIZE	(WCID_END - WCID_START + 2)
+#define CHAIN_0		0x0
+#define CHAIN_1		0x1
+#define RF_ALC_NUM	6
+#define CHAIN_NUM	2
+
+struct rf_reg_pair {
+	u8 bank;
+	u8 reg;
+	u8 value;
+};
 
 /* RT2800 driver data structure */
 struct rt2800_drv_data {