dt-bindings: Document STM32 CRYP bindings

Document device tree bindings for the STM32 CRYP.
Signed-off-by: Fabien Dessenne <fabien.dessenne@st.com>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

Documentation/devicetree/bindings/crypto/st,stm32-cryp.txt

+* STMicroelectronics STM32 CRYP
+
+Required properties:
+- compatible: Should be "st,stm32f756-cryp".
+- reg: The address and length of the peripheral registers space
+- clocks: The input clock of the CRYP instance
+- interrupts: The CRYP interrupt
+
+Optional properties:
+- resets: The input reset of the CRYP instance
+
+Example:
+crypto@50060000 {
+	compatible = "st,stm32f756-cryp";
+	reg = <0x50060000 0x400>;
+	interrupts = <79>;
+	clocks = <&rcc 0 STM32F7_AHB2_CLOCK(CRYP)>;
+	resets = <&rcc STM32F7_AHB2_RESET(CRYP)>;
+};