[nrf noup] dts: add binding file for cc132 cryptocell sw

Add a binding file for nordic,nrf-cc312-sw.

Signed-off-by: Ioannis Glaropoulos <Ioannis.Glaropoulos@nordicsemi.no>

dts/bindings/crypto/nordic,nrf-cc312-sw.yaml

@@ -0,0 +1,17 @@
+# Copyright (c) 2021, Nordic Semiconductor ASA
+# SPDX-License-Identifier: Apache-2.0
+
+description: |
+  Stub access to cryptocell via platform driver
+
+  Non-secure configurations can use this compatible to declare
+  devicetree nodes which access the CC312 via callbacks into secure
+  code.
+
+compatible: "nordic,nrf-cc312-sw"
+
+include: base.yaml
+
+properties:
+  label:
+    required: true