dt-bindings: iio: adc: exynos-adc: Add S5PV210 variant

Add information about new compatible for S5PV210
Signed-off-by: Jonathan Bakker <xc-racer2@live.ca>
Signed-off-by: Paweł Chmiel <pawel.mikolaj.chmiel@gmail.com>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Documentation/devicetree/bindings/iio/adc/samsung,exynos-adc.txt

@@ -11,7 +11,7 @@ New driver handles the following
 
 Required properties:
 - compatible:		Must be "samsung,exynos-adc-v1"
-				for exynos4412/5250 and s5pv210 controllers.
+				for exynos4412/5250 controllers.
 			Must be "samsung,exynos-adc-v2" for
 				future controllers.
 			Must be "samsung,exynos3250-adc" for
@@ -28,6 +28,8 @@ Required properties:
 				the ADC in s3c2443 and compatibles
 			Must be "samsung,s3c6410-adc" for
 				the ADC in s3c6410 and compatibles
+			Must be "samsung,s5pv210-adc" for
+				the ADC in s5pv210 and compatibles
 - reg:			List of ADC register address range
 			- The base address and range of ADC register
 			- The base address and range of ADC_PHY register (every