iio: adc: sc27xx: fix read big scale voltage not right

Fix wrong configuration value of SC27XX_ADC_SCALE_MASK and
SC27XX_ADC_SCALE_SHIFT by spec documetation.

Fixes: 5df362a6 (iio: adc: Add Spreadtrum SC27XX PMICs ADC support)
Signed-off-by: Cixi Geng <cixi.geng1@unisoc.com>
Reviewed-by: Baolin Wang <baolin.wang7@gmail.com>
Link: https://lore.kernel.org/r/20220419142458.884933-3-gengcixi@gmail.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/sc27xx_adc.c

@@ -36,8 +36,8 @@
 
 /* Bits and mask definition for SC27XX_ADC_CH_CFG register */
 #define SC27XX_ADC_CHN_ID_MASK		GENMASK(4, 0)
-#define SC27XX_ADC_SCALE_MASK		GENMASK(10, 8)
-#define SC27XX_ADC_SCALE_SHIFT		8
+#define SC27XX_ADC_SCALE_MASK		GENMASK(10, 9)
+#define SC27XX_ADC_SCALE_SHIFT		9
 
 /* Bits definitions for SC27XX_ADC_INT_EN registers */
 #define SC27XX_ADC_IRQ_EN		BIT(0)