dt-bindings: BD718x7 - add missing I2C bus properties

The DT example needs #address-cells and #size-cells for I2C bus or
validity checker will generate warnings. Add these properties in
BD71837 and BD71847 binding examples.

Signed-off-by: Matti Vaittinen <[e-mail]>
Signed-off-by: Rob Herring <[e-mail]>

Documentation/devicetree/bindings/mfd/rohm,bd71837-pmic.yaml

···
     #include <dt-bindings/leds/common.h>
 
     i2c {
-      pmic: pmic@4b {
+        #address-cells = <1>;
+        #size-cells = <0>;
+        pmic: pmic@4b {
             compatible = "rohm,bd71837";
             reg = <0x4b>;
             interrupt-parent = <&gpio1>;

Documentation/devicetree/bindings/mfd/rohm,bd71847-pmic.yaml

···
     #include <dt-bindings/leds/common.h>
 
     i2c {
-      pmic: pmic@4b {
+        #address-cells = <1>;
+        #size-cells = <0>;
+        pmic: pmic@4b {
             compatible = "rohm,bd71847";
             reg = <0x4b>;
             interrupt-parent = <&gpio1>;