sandbox: Add a test for SCSI

Add a simple uclass test for SCSI. It reads the partition table from a
disk image and checks that it looks correct.

Signed-off-by: Simon Glass <sjg@chromium.org>

arch/sandbox/dts/sandbox.dtsi

@@ -245,6 +245,10 @@
 		compatible = "sandbox,sandbox-rng";
 	};
 
+	scsi {
+		compatible = "sandbox,scsi";
+	};
+
 	sound {
 		compatible = "sandbox,sound";
 		cpu {

arch/sandbox/dts/test.dts

@@ -1158,6 +1158,11 @@
 		backlight = <&backlight 0 100>;
 	};
 
+	scsi {
+		compatible = "sandbox,scsi";
+		sandbox,filepath = "scsi.img";
+	};
+
 	smem@0 {
 		compatible = "sandbox,smem";
 	};