dt-bindings: nvmem: add common definition of nvmem-cell-cells

Linux kernel NVMEM consumer bindings define phandle to NVMEM cells
("nvmem-cells"), thus we also want the common definition of property
defining number of cells encoding that specifier, so the

Suggested-by: Rob Herring <robh@kernel.org>
Reported-by: Michael Walle <michael@walle.cc>
Closes: devicetree-org/dt-schema#89
Reported-by: Rafał Miłecki <zajec5@gmail.com>
Closes: https://lore.kernel.org/linux-arm-kernel/20221121105830.7411-1-zajec5@gmail.com/#r
Closes: https://lore.kernel.org/all/bdf7751b-0421-485d-8382-26c084f09d7d@gmail.com/
Signed-off-by: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>

Documentation/devicetree/bindings/nvmem/nvmem-provider.yaml

@@ -0,0 +1,18 @@
+# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/nvmem/nvmem-provider.yaml#
+$schema: http://devicetree.org/meta-schemas/base.yaml#
+
+title: NVMEM (Non Volatile Memory) Provider
+
+maintainers:
+  - Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
+
+select: true
+
+properties:
+  '#nvmem-cell-cells':
+    enum: [0, 1]
+
+additionalProperties: true