iio: light: apds9960: fix wrong register for gesture gain

Gesture Gain Control is in REG_GCONF_2 (0xa3), not in REG_CONFIG_2 (0x90).

Fixes: aff268c ("iio: light: add APDS9960 ALS + promixity driver")
Signed-off-by: Alejandro Concepcion-Rodriguez <asconcepcion@acoro.eu>
Acked-by: Matt Ranostay <matt.ranostay@konsulko.com>
Cc: <Stable@vger.kernel.org>
Link: https://lore.kernel.org/r/EaT-NKC-H4DNX5z4Lg9B6IWPD5TrTrYBr5DYB784wfDKQkTmzPXkoYqyUOrOgJH-xvTsEkFLcVkeAPZRUODEFI5dGziaWXwjpfBNLeNGfNc=@acoro.eu
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Author: asconcepcion

drivers/iio/light/apds9960.c

@@ -54,9 +54,6 @@
 #define APDS9960_REG_CONTROL_PGAIN_MASK_SHIFT	2
 
 #define APDS9960_REG_CONFIG_2	0x90
-#define APDS9960_REG_CONFIG_2_GGAIN_MASK	0x60
-#define APDS9960_REG_CONFIG_2_GGAIN_MASK_SHIFT	5
-
 #define APDS9960_REG_ID		0x92
 
 #define APDS9960_REG_STATUS	0x93
@@ -77,6 +74,9 @@
 #define APDS9960_REG_GCONF_1_GFIFO_THRES_MASK_SHIFT	6
 
 #define APDS9960_REG_GCONF_2	0xa3
+#define APDS9960_REG_GCONF_2_GGAIN_MASK			0x60
+#define APDS9960_REG_GCONF_2_GGAIN_MASK_SHIFT		5
+
 #define APDS9960_REG_GOFFSET_U	0xa4
 #define APDS9960_REG_GOFFSET_D	0xa5
 #define APDS9960_REG_GPULSE	0xa6
@@ -396,9 +396,9 @@ static int apds9960_set_pxs_gain(struct apds9960_data *data, int val)
 			}
 
 			ret = regmap_update_bits(data->regmap,
-				APDS9960_REG_CONFIG_2,
-				APDS9960_REG_CONFIG_2_GGAIN_MASK,
-				idx << APDS9960_REG_CONFIG_2_GGAIN_MASK_SHIFT);
+				APDS9960_REG_GCONF_2,
+				APDS9960_REG_GCONF_2_GGAIN_MASK,
+				idx << APDS9960_REG_GCONF_2_GGAIN_MASK_SHIFT);
 			if (!ret)
 				data->pxs_gain = idx;
 			mutex_unlock(&data->lock);