doc: device-tree-bindings: add Sandbox TPMv2.0 module info

Add Sandbox TPMv2.0 module bindings.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Tom Rini <trini@konsulko.com>

doc/device-tree-bindings/tpm2/sandbox.txt

@@ -0,0 +1,11 @@
+Sandbox TPMv2.0 bindings
+------------------------
+
+Required properties:
+- compatible		: Should be "sandbox,tpm2"
+
+Example:
+
+	tpm {
+ 		compatible = "sandbox,tpm2";
+	};