dt-bindings: iio/adc: ingenic: add the JZ4760(B) socs to the sadc Documentation

Add both the jz4760 and jz4760b, plus a property to use the internal
divider on the b variant and document it.

Signed-off-by: Christophe Branchereau <cbranchereau@gmail.com>
Reviewed-by: Rob Herring <robh@kernel.org>
Link: https://lore.kernel.org/r/20210726082033.351533-6-cbranchereau@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

Documentation/devicetree/bindings/iio/adc/ingenic,adc.yaml

@@ -23,6 +23,8 @@ properties:
     enum:
       - ingenic,jz4725b-adc
       - ingenic,jz4740-adc
+      - ingenic,jz4760-adc
+      - ingenic,jz4760b-adc
       - ingenic,jz4770-adc
 
   '#io-channel-cells':
@@ -43,6 +45,23 @@ properties:
   interrupts:
     maxItems: 1
 
+  ingenic,use-internal-divider:
+    description:
+      If present, battery voltage is read from the VBAT_IR pin, which has an
+      internal 1/4 divider. If absent, it is read through the VBAT_ER pin,
+      which does not have such a divider.
+    type: boolean
+
+if:
+  not:
+    properties:
+      compatible:
+        contains:
+          const: ingenic,jz4760b-adc
+then:
+  properties:
+    ingenic,use-internal-divider: false
+
 required:
   - compatible
   - '#io-channel-cells'