dt-bindings: rtc: ti,bq32k: Convert to json-schema

Convert the TI BQ32000 I2C Serial Real-Time Clock Device Tree binding
documentation to json-schema.

Document missing properties.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Rob Herring <robh@kernel.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Link: https://lore.kernel.org/r/42d9c71b4ee1f120e0cdcf6b266547d29d1fb9a4.1623851377.git.geert+renesas@glider.be

Documentation/devicetree/bindings/rtc/ti,bq32000.yaml

+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/rtc/ti,bq32000.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: TI BQ32000 I2C Serial Real-Time Clock
+
+maintainers:
+  - Pavel Machek <pavel@ucw.cz>
+
+allOf:
+  - $ref: rtc.yaml#
+
+properties:
+  compatible:
+    const: ti,bq32000
+
+  reg:
+    const: 0x68
+
+  interrupts:
+    maxItems: 1
+
+  start-year: true
+
+  trickle-resistor-ohms:
+    enum: [ 1120, 20180 ]
+
+  trickle-diode-disable: true
+
+required:
+  - compatible
+  - reg
+
+additionalProperties: false
+
+examples:
+  - |
+    i2c {
+            #address-cells = <1>;
+            #size-cells = <0>;
+
+            bq32000: rtc@68 {
+                    compatible = "ti,bq32000";
+                    reg = <0x68>;
+                    trickle-resistor-ohms = <1120>;
+            };
+    };

Documentation/devicetree/bindings/rtc/ti,bq32k.txt

-* TI BQ32000                I2C Serial Real-Time Clock
-
-Required properties:
-- compatible: Should contain "ti,bq32000".
-- reg: I2C address for chip
-
-Optional properties:
-- trickle-resistor-ohms : Selected resistor for trickle charger
-       Values usable are 1120 and 20180
-       Should be given if trickle charger should be enabled
-- trickle-diode-disable : Do not use internal trickle charger diode
-       Should be given if internal trickle charger diode should be disabled
-Example:
-       bq32000: rtc@68 {
-               compatible = "ti,bq32000";
-               trickle-resistor-ohms = <1120>;
-               reg = <0x68>;
-       };