dt-bindings: hwmon: add common properties

Add a common hwmon schema for two properties:
1. "label", because Linux hwmon core code parses it.
2. "shunt-resistor-micro-ohms", because several devices already use it.
Acked-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
Link: https://lore.kernel.org/r/20240224-dt-bindings-hwmon-common-v2-1-b446eecf5480@linaro.orgSigned-off-by: Guenter Roeck <linux@roeck-us.net>

Documentation/devicetree/bindings/hwmon/hwmon-common.yaml

+# SPDX-License-Identifier: GPL-2.0 OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/hwmon/hwmon-common.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Hardware Monitoring Devices Common Properties
+
+maintainers:
+  - Guenter Roeck <linux@roeck-us.net>
+
+properties:
+  label:
+    description: A descriptive name for this device.
+
+  shunt-resistor-micro-ohms:
+    description: The value of current sense resistor.
+
+additionalProperties: true