dt-bindings: iio: adc: exynos: Remove old requirement of two register address ranges

Commit fafb37cf ("iio: exyno-adc: use syscon for PMU
register access") changed the Exynos ADC driver so the PMU syscon
phandle is required instead of second register address space.  The
bindings were not updated so fix them now.
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Rob Herring <robh@kernel.org>

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

@@ -25,8 +25,7 @@ properties:
       - samsung,s5pv210-adc
 
   reg:
-    minItems: 1
-    maxItems: 2
+    maxItems: 1
 
   clocks:
     description:
@@ -55,7 +54,7 @@ properties:
     $ref: '/schemas/types.yaml#/definitions/phandle'
     description:
       Phandle to the PMU system controller node (to access the ADC_PHY
-      register on Exynos5250/5420/5800/3250).
+      register on Exynos3250/4x12/5250/5420/5800).
 
   has-touchscreen:
     description:
@@ -83,19 +82,8 @@ allOf:
               - samsung,exynos4212-adc
               - samsung,s5pv210-adc
     then:
-      properties:
-        reg:
-          items:
-            # For S5P and Exynos
-            - description: base registers
-            - description: phy registers
       required:
         - samsung,syscon-phandle
-    else:
-      properties:
-        reg:
-          items:
-            - description: base registers
 
   - if:
       properties: