dts: arm: stm32: Add rcc node yaml descritpion

Provide rcc node yaml description for stm32 socs

Signed-off-by: Erwan Gouriou <erwan.gouriou@linaro.org>

dts/arm/yaml/st,stm32-rcc.yaml

diff --git a/dts/arm/yaml/st,stm32-rcc.yaml b/dts/arm/yaml/st,stm32-rcc.yaml
new file mode 100644
index 0000000..e35d9ce
--- /dev/null
+++ b/dts/arm/yaml/st,stm32-rcc.yaml
@@ -0,0 +1,28 @@
+---
+title: STM32 RCC
+id: st,stm32-rcc
+version: 0.1
+
+description: >
+    This binding gives a base representation of the STM32 Clock control
+
+properties:
+  - compatible:
+      type: string
+      category: required
+      description: compatible strings
+      constraint: "st,stm32-rcc"
+
+  - reg:
+      type: array
+      description: mmio register space
+      generation: define
+      category: required
+
+cell_string: clocks
+
+"#cells":
+  - bus
+  - bits
+
+...