sandbox: dt: add sandbox_tee node

Adds a sandbox_tee node to enable the sandbox tee driver in all the
sandbox dts files.

Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>
diff --git a/arch/sandbox/dts/sandbox64.dts b/arch/sandbox/dts/sandbox64.dts
index 9e65d2f..0e32fda 100644
--- a/arch/sandbox/dts/sandbox64.dts
+++ b/arch/sandbox/dts/sandbox64.dts
@@ -311,6 +311,10 @@
 			};
 		};
 	};
+
+	sandbox_tee {
+		compatible = "sandbox,tee";
+	};
 };
 
 #include "cros-ec-keyboard.dtsi"