dt-bindings: crypto: add ARTPEC crypto

Document the device tree bindings for the ARTPEC crypto accelerator on
ARTPEC-6 and ARTPEC-7 SoCs.
Acked-by: NRob Herring <robh@kernel.org>
Signed-off-by: NLars Persson <larper@axis.com>
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>

Documentation/devicetree/bindings/crypto/artpec6-crypto.txt

+Axis crypto engine with PDMA interface.
+
+Required properties:
+- compatible : Should be one of the following strings:
+	"axis,artpec6-crypto" for the version in the Axis ARTPEC-6 SoC
+	"axis,artpec7-crypto" for the version in the Axis ARTPEC-7 SoC.
+- reg: Base address and size for the PDMA register area.
+- interrupts: Interrupt handle for the PDMA interrupt line.
+
+Example:
+
+crypto@f4264000 {
+	compatible = "axis,artpec6-crypto";
+	reg = <0xf4264000 0x1000>;
+	interrupts = <GIC_SPI 19 IRQ_TYPE_LEVEL_HIGH>;
+};